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Evidence for Multiple Structural Genes for the gamma Chain of Human Fetal Hemoglobin

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... Since damaged red cells are released into the peripheral circulation due to ineffective erythropoiesis, there occurs extravascular hemolysis. [9][10][11][12] ...
... The affected individuals exhibit no clinical abnormalities and may be hematologically normal or have mild reductions in RBC, MCV, and MCH MCV: Mean corpuscular volume; MCH: Mean corpuscular hemoglobin and δ-globulin chains. 12,13 Various forms of β-thalassemia has been illustrated in Table 2. ...
... The changes leading to the overexpression of TAL1 are considered to be the most common tumor-specific chromosomal abnormalities found in human T cell acute lymphoblastic leukemia (T-ALL). In addition, studies have confirmed that TAL1 is involved in malignant transformation and demonstrated that it can act synergistically with other oncogens to accelerate tumor formation (Robb et al., 1997;Schroeder et al., 1968). ...
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After the revelation of the DNA double helix structure by Watson and Crick in the year 1953, a spectacular chain of progressions has been made in the understanding of the human genome organization and function. Genes involved in diseases such as Huntington and Cystic Fibrosis had already been identified and mapped before the Human Genome Project (HGP) started in 1989. But it was not until the year 2013, which coincided with the 50th anniversary of the discovery of DNA structure, when the HGP had been finished and the final version of the human genome got public. Although this event alone led to a huge step forward in medical research, scientists are still on track in solving the nature of many diseases. Meanwhile, plastic surgeons had little interest on those achievements; although, molecular biology and genomics might also provide answers to many problems of this specialty. Nevertheless, by pioneering research some progress has also been made in this field and this review aims to reveal how far and dense this area has gone today.
... The g-globin chains (HBG2 and HBG1) characterizing fetal hemoglobin (HbF) are encoded by 2 nonallelic linked genes, HBG2 and HBG1, whose polypeptides differ (136 glycine in HBG2 and 136 alanine in HBG1). 1,2 Expression quantitative trait loci (QTL) can be used as a quantitative phenotype to ascertain the expression of individual genes, such as HBG2 and HBG1, and to provide insight into whether HbF QTL effect 1 or both g-globin genes (together referred to as HBG). Using the Genotype-Tissue Expression database, we studied HBG gene expression along with the regulatory elements of these genes and the effects of genetic variations of these elements. ...
Article
Fetal hemoglobin (HbF) expression is partially governed by the trans-acting quantitative trait loci BCL11A and MYB and a cis-acting locus linked to the HBB gene cluster. Our previous analysis of the Genotype-Tissue Expression database suggested that BCL2L1 was associated with HbF gene expression. In erythroid progenitors from patients with sickle cell disease, BCL2L1 messenger RNA (mRNA) levels were positively correlated with HBG mRNA and total HbF concentration (r2 = 0.72, P = .047 and r2 = 0.68, P = .01, respectively). Inhibition of BCL2L1 protein activity in HbF-expressing HUDEP-1 cells decreased HBG expression in a dose-dependent manner. Overexpression of BCL2L1 in these cells increased HBG expression fourfold (P < .05) and increased F cells by 13% (P < .05). Overexpression of BCL2L1 in erythroid progenitors derived from primary adult CD34+ cells upregulated HBG expression 11-fold (P < .05), increased F cells by 18% (P < .01), did not significantly affect cell differentiation or proliferation, and had a minor effect on survival. Although the mechanism remains unknown, our results suggest that BCL2L1 is associated with HbF gene activation.
... The changes leading to the overexpression of TAL1 are considered to be the most common tumor-specific chromosomal abnormalities found in human T cell acute lymphoblastic leukemia (T-ALL). In addition, studies have confirmed that TAL1 is involved in malignant transformation and demonstrated that it can act synergistically with other oncogens to accelerate tumor formation (Robb et al., 1997;Schroeder et al., 1968). ...
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This chapter presents an overview of deep learning (DL) structures in pulmonary cancer diagnosis. It is divided into three parts. In this first section, an introduction to pulmonary cancer diagnosis has given along with an overview of related research in this field. Hereafter, deep learning algorithms used in the diagnosis of pulmonary cancer is presented in section 2. In section 3, commercial software programs serving radiologists in the diagnosis of pulmonary cancer are outlined. The chapter of the book has been prepared especially for software developers who want to work on pulmonary cancer diagnosis First Edition • © ŞUBAT 2021 ISBN • 978-625-7342-78-0 Citation can not be shown without the source, reproduced in any way without permission.
... The thalassemias are among the most common genetic disorders worldwide, occurring more frequently in the Mediterranean ], the Indian subcontinent, Southeast Asia, and West ]. Ineffective bone marrow erythropoiesis and excessive red blood cell hemolysis together account for the anemia.Since reticulocytes manufacture equimolecular quantities of alpha and beta chains, mature erythrocytes contain essentially equimolecular amounts of each chain [3]. nts with thalassemia do not produce enough ) because their cells cannot manufacture either the alpha or beta polypeptide chain of thalassemia depresses only the production of the alpha chains, and beta-thalassemia depresses only the production of the beta chains. ...
... There is only an amino acid difference between G γ and A γ globin genes. This difference located at codon 136, while G γ has glycine at this location, has alanine (14). The variations that were defined in this study have been identified previously as described in GenBank database (GU324926 and GU324925), except the -567T/G variation in G γ globin gene which has been observed and defined for the first time by this study. ...
Article
In the present study, sixty-two samples that have 1.5% and upper level of fetal hemoglobin (HbF), were examined to investigate the relationship between HbF level and non-deletional mutations in both Gγ (G gamma) globin (HBG2) and Aγ (A gamma) globin (HBG1) genes. Four variations were observed in the promotor of Gγ gene, which are -158C/T, -309A/G, -369C/G, and -567T/G. Also, four variations were observed in the 5'-UTR (untranslated regions) and promotor of Aγ gene, which are +25G/A, -369G/C, -499T/A, and -588G/A. One -222/-225 AGCA del homozygous and six variations as heterozygous in A gamma globin gene promotor region were also observed. The results of the current study suggested that there was a significant relationship between high HbF levels and two variations (-309A/T and -369C/G) in Gγ gene promotor. Additionally, a significant relationship between two variations (+25G/A and -499T/A) in Aγ gene promotor was also observed. Furthermore, the persons who carry these variations with high levels of HbF indicated that there might be a haplotype effect between these variations.
... Gene duplication is responsible for the two fetal genes G γ-and A γ-globin. The coding region of each γ-globin gene are identical except at amino acid residue 136 where a glycine is present in G γ-globin and an alanine in A γ-globin [31]. The promoter of each γ-globin gene contains a TATA box, two CAAT Boxes, and one CACCC box [1]. ...
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The developmental regulation of the γ-to β-globin switch has motivated research efforts to establish therapeutic modalities for individuals affected with β-hemoglobinopathies. Fetal Hemoglobin (HbF) synthesis is high at birth but declines to adult levels by one year of ages; since HbF blocks hemoglobin S polymerization in Sickle Cell Disease (SCD) and compensated for anemia in β-Thalassemia, reactivating expression is of great research interest. Naturally occurring mutations in the β-globin locus on chromosome 11, produce elevated HbF expression after birth which ameliorates symptoms in SCD. Genome-wide studies discovered three gene loci including BCL11A that account for the majority of inherited HbF variance but considerable work is required to advance this protein as a therapeutic target. Therefore, efforts to develop chemical inducers of HbF are desirable. Hydroxyurea is a potent HbF inducer with clinical efficacy in adults and children with SCD but it has been underutilized in the clinical setting. Numerous pharmacological agents that reactivate γ-gene transcription have been discovered over the last three decades but few have been translated into clinical therapeutics. We will review the progress made in understanding molecular mechanisms of γ-globin regulation and current efforts to expand the number of chemical HbF inducers available for treatment of patients with β-hemoglobinopathies.
... The g-globin subunits, which characterize HbF, are encoded by two closely linked genes-from 5' to 3', HBG2 and HBG1 (together, HBG). The respective polypeptides of the g-globin genes differ by only a single amino acid in position 136; glycine in the G g chain (HBG2) and alanine in the A g chain (HBG1) (Schroeder et al. 1968). In adults, these genes are expressed at a ratio of 2:3 (Terasawa et al. 1980). ...
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Genetic association studies have detected two trans-acting quantitative trait loci (QTL) on chromosomes 2, 6 and one cis-acting QTL on chromosome 11 that were associated with fetal hemoglobin (HbF) levels. In these studies, HbF was expressed as a percentage of total hemoglobin or the number of erythrocytes that contain HbF (F-cells). As the γ -globin chains of HbF are encoded by two non-allelic genes (HBG2, HBG1) that are expressed at different levels we used normalized gene expression and genotype data from The Genotype-Tissue Expression (GTEx)-project to study the effects of cis- and trans-acting HbF expression or eQTL. This allowed us to examine mRNA expression of HBG2 and HBG1individually. In addition to studying eQTL for globin genes we examined genes co-expressed with HBG1 , studied upstream regulators of HBG1 co-expressed genes and performed a correlation analysis between HBG2 and HBG1 and known HbF regulators. Our results suggest differential effect of cis and trans-acting QTL on HBG and HBG1 expression. Trans-acting eQTLs have the same magnitude of effect on the expression of both HBG2 and HBG1 while the sole cis-acting eQTL affected only HBG2 . Furthermore, the analysis of upstream regulators and the correlation analysis suggested that BCL2L1 might be a new potential trans-acting HbF activator. HbF is the major modulator of the phenotype of sickle cell anemia and β thalassemia. Depending on the effect size, modification of trans-acting elements might have a greater impact on HbF levels than cis-acting elements alone.
Article
. A Gγ-chain variant, Hb F Port Royal, with an electrophoretic mobility intermediate between Hb S and Hb C, was found in a Jamaican-Negro infant, and made up 14–15% of the total Hb F. A glycinamidation procedure was employed to aid in determining the amino-acid residue substitution of γ125Glu → Ala, and the presence of glycinc in position 136.
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Bis heute ist Hämoglobin ein bevorzugtes Objekt der molekularen Biologie. Die Untersuchungen dieses Moleküls gipfeln in der vollständigen atomaren Beschreibung seiner Struktur in verschiedenen Funktionszuständen und sind beispielhaft für die Erforschung von anderen Biopolymeren. Die Kenntnis der Anatomie dieses Proteins setzt uns allerdings noch nicht in den Stand, quantitative Voraussagen über seine Funktion zu machen.
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All animals that use hemoglobin for oxygen transport synthesize different hemoglobin types during the various stages of development. In humans, two gene clusters direct the production of hemoglobin including the α-locus which contains the embryonic ζ gene and two adult α genes on chromosome 16. A second cluster, the β-globin locus located on chromosome 11, contains the ε, Gγ, Aγ, δ, and β genes. The globin genes are arranged from 5′ to 3′ according to the order of their expression and are developmentally regulated to produce different hemoglobin species during ontogeny. Two switches in the type of hemoglobin synthesized during development occur, a process known as hemoglobin switching. Through research efforts over the last two decades, several insights have been gained into the molecular mechanisms of hemoglobin switching. However, the entire process has not been fully elucidated. Studies of naturally occurring globin gene promoter mutations and transgenic mouse investigations have contributed to our understanding of the effect of DNA mutations on globin gene expression. Furthermore, the developmental regulation of globin gene expression has shaped research efforts to establish therapeutic modalities for individuals affected with sickle cell disease and β-thalassemia. Here, we will review the progress made toward understanding molecular mechanisms that control globin gene expression and the consequences of mutations on hemoglobin switching.
Article
High levels of fetal hemoglobin (HbF) can ameliorate human β-globin gene disorders. The short chain fatty acid butyrate is the paradigmatic metabolic intermediary that induces HbF. Inherited disorders of branched-chain amino acid (BCAA) metabolism have been associated with supranormal HbF levels beyond infancy, e.g., propionic acidemia (PA) and methylmalonic acidemia (MMA). We tested intermediaries of BCAA metabolism for their effects on definitive erythropoiesis. Like butyrate, the elevated BCAA intermediaries isovalerate, isobutyrate, and propionate, induce fetal globin gene expression in murine EryD in vitro, are associated with bulk histone H3 hyperacylation, and repress the transcription of key gamma globin regulatory factors, notably BCL11A and SOX6. Metabolic intermediaries that are elevated in Maple Syrup Urine Disease (MSUD) affect none of these processes. Percent HbF and gamma (γ) chain isoforms were also measured in non-anemic, therapeutically optimized subjects with MSUD (Group I, n=6) or with Isovaleric Acidemia (IVA), MMA, or PA (Group II, n=5). Mean HbF was 0.24±0.15% in Group I and 0.87±0.13% in Group II (p=.01); only the Gγ isoform was detected. We conclude that a family of biochemically related intermediaries of branched chain amino acid metabolism induces fetal hemoglobin during definitive erythropoiesis, with mechanisms that mirror those so far identified for butyrate. Copyright © 2015 Elsevier Inc. All rights reserved.
The human foetal haemoglobin consists of α and γ chains of which the latter may either have a residue of alanine or of glycine at position 136. The γ chain of the human foetal haemoglobin variant haemoglobin F Texas I, which has a substitution Glu → Lys in position 5 was found to have an alanine at position 136.
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Objectifs : Déterminer l’influence du taux d’hémoglobine F sur le profil évolutif dans la drépanocytose homozygote.Patients et méthodes : Il s’est agi d’une étude rétrospective descriptive portant sur 191 sujets drépanocytaires homozygotes régulièrement suivis dans le service des laboratoires du CHU-Campus de Lomé durant la période allant de janvier 1997 à décembre 2006 (10 ans).Résultats : Durant la période d’étude, 191 dossiers sur 306 répondaient aux critères d’inclusion. L’âge moyen était de 18,93 ± 12,25 ans avec des extrêmes de 16 mois et 75 ans. Il existait une légère prédominance masculine avec une sex-ratio de 1,17. La population étudiée était repartie en trois groupes en fonction du taux d’HbF. Le taux moyen d’HbF était de 16,61 ± 10,17 %.Quatre types de complications avaient été notées. Les complications anémiques et ischémiques étaient plus fréquentes chez les patients à taux d’HbF bas. Les complications neurologiques n’étaient retrouvées dans notre étude que chez les patients à taux d’HbF supérieur à 20%. Le taux d’HbF ne semble pas avoir d’influence sur la survenue des complications infectieuses.Conclusion : L’évolution du drépanocytaire homozygote est fortement influencée par son taux d’HbF. Les complications sont moindres lorsque le taux d’Hb F est élevé.Mots clés : drépanocytose, hémoglobine foetale, évolution, complicationsObjectives: To determine the influence of hemoglobin F level on the evolution in sickle cell disease.Patients and methods: A total of 191 sickle cell disease (SCD) patients were enrolled in a descriptive retrospective study. Patients were regularly followed in the laboratories service of Campus teaching hospital in Lome lasting the period going from January 1997 to December 2006 (10 years).Results: During the period of study, 191 files out of 306 answered the criteria of inclusion. The average age was 18.93 ± 12.25 years with extremes of 16 month and 75 years. There was a light male prevalencewith a sex-ratio of 1.17. The studied population had set out again in three groups according to the rate of HbF. The average rate of HbF was 16.61 ± 10.17 %.Four complications group had been noted. The anemic and ischemic complications were more frequent among patients with low HbF level. The neurological complications were found only among patients with HbF level higher than 20%. The rate of HbF does not seem to have of influence on which has occurred of the infectious complications.Conclusion: The evolutionary profile of the SCD is strongly influenced by its rate of HbF.
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A combination of 2 forms of thalassemia has been observed in a member of a South Carolina family. The proposita, a 34-year-old black female with hemolytic anemia, had over 50% fetal hemoglobin, an elevated level of hemoglobin A2, and in vitro imbalance in chain synthesis. Family studies revealed a δβ-thalassemia heterozygosity in her mother and 2 sibs and a β-thalassemia heterozygosity in her son. The fetal hemoglobin of the δβ heterozygotes was of the Gγ type (i.e., the γ chain had glycine in position 136). Consequently, it may be concluded that the propositus has Gγ-δβ-thalassemia-β+ thalassemia; this is the first time that such a combination has been recognized. In 3 members of another family this same type of Gγ-δβ-thalassemia occurred in combination with Hb S, whereas Gγ-β°-HPFH (hereditary persistence of fetal hemoglobin) and Hb S were present in 1 member of a third family. Clinical features and laboratory findings were specific for each condition and permitted a clear distinction between Gγ-δβ-thalassemia and Gγ-β°-HPFH. The discussion correlates these findings with data from 80 persons in 30 families whose Hb F was elevated and contained only Gγ chains.
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Clinical, hæmatological, genetic, chemical, and oxygen-affinity studies have been carried out on a group of 18 Shiite Saudi Arabians with sickle-cell anæmia. Apart from occasional attacks of mild musculo-skeletal pain they are well and have few of the complications which are usual in the sickling disorders. The unusually mild course of the illness is attributable, at least in part, to a genetically determined ability to produce large amounts of fetal hæmoglobin.
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Riassunto Sono messi in evidenza i progressi più recenti delle nostre conoscenze sulle emoglobine normali e su quelle patologiche. Viene fatta una dettagliata analisi delle differend emoglobine patologiche, distinte secondo il tipo di alterazione: cioè quelle con difetto di struttura e quelle in cui esiste una turba nella capacità di sintesi delle varie catene emoglobiniche. Tra 1e prime vengono esaminate in particolare quelle con emoglobina instabile; tra le seconde 1e talassemie e 1e sue numerose varianti. Uno dei dati più importanti che emergono da questa esposizione è quello dei rapporti tra posizione spaziale delle mutazioni nella molecola emoglobinica e gravità delia rispettiva malattia. Si dà cioè valore non solo alle alterazioni della struttura primaria e delle sequenze aminoacidiche ma anche e soprattutto alle variazioni indotte nella struttura tridimensionale. Sono riportati molti esempi di emoglobine patologiche, parecchie delle quali di osservazione personale. Viene infine ricordata 1a note-vole frequenza dei difetti emoglobinici nella popolazione italiana.
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Summary Cord blood samples, collected at Sousse and Monastir, from Tunisian newborns were focused on a thin layer of agarose in order to detect the carriers of the Aγ75Thr chain (Aγ chain bearing a replacement Ile→Thr at position 75). Nineteen individuals (10%) were positive for this variant. The frequency of the Aγ75Thr gene in the Tunisian population (0.050) is compared with that of various ethnic populations.
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The thalassemias, sickle cell disease, and other hemoglobinopathies represent a major group of inherited disorders of hemoglobin synthesis. The abnormal hemoglobins were reviewed in the July 2006 issue of Baylor University Medical Center Proceedings. Because of immigration patterns and population flow, these disorders are becoming increasingly more prevalent in the USA. In this article, the clinical aspects of the more common thalassemia syndromes are reviewed. For most symptomatic patients with thalassemia, there is no definite cure; only supportive management of the anemia is possible. A very limited number of patients with thalassemia may be cured by bone marrow transplantation from HLA-identical donors. Other tentative approaches to management include stimulation of fetal hemoglobin synthesis and attempts at somatic cell gene therapy. Prevention of disease transmission by carrier screening programs along with prenatal diagnosis remain of paramount importance in the reduction of these diseases worldwide.
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Starch gel electrophoresis was carried out by standard methods4. Samples of purified haemoglobin Ho-2 were prepared by chromatography on 'DEAE-Sephadex', as described by Huisman et al.5. The ? and the β-chains were separated from one another and fingerprints on paper were prepared as described by Clegg et al.6. Peptides were eluted from fingerprints into 100 ??.
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Blood samples were taken from twelve foetal and thirty-four infant macaques ranging in age from the sixtieth day of gestation to 86 days postpartum. Foetuses were taken by Caesarean section and bled by direct cardiac puncture.
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The proportions of G? and A? globins in hemoglobin F were determined in fetuses around the 20th week of gestation, newborns, and children 3 weeks to 5 months of age. In the last group, the G?/G? + A? ratio decreased continously; there was a good correlation between the decline of G? with respect to total ? and the decline of Hb F (r=0.88). In contrast, there was virtually no difference in the ? globin composition of Hb F between the fetuses and the newborns, i.e. in late pregnancy, the decrease in the synthesis of both ? globins appears to be proportionate. The G? and A? globin genes may be inactivated in a sigmoidal fashion with time, thus producing a G?/G? + A? ratio which at first changes only slightly and then declines linearily.
Article
Elsewhere I presented evidence for the existence of more than one variant of the ? chain of rabbit haemoglobin8. These variants have more than one amino-acid in at least three positions.
Chapter
The introduction of electrophoretic techniques in the early 1950s soon led to the discovery that the haemoglobins of many animal species are polymorphic. In man the crucial discovery of haemoglobin S in the red cells of persons with sickle-cell anaemia was a striking illustration of the concept of disease at the molecular level, and it subsequently stimulated a great deal of research into the genetic aspects of the control of protein synthesis. Early ideas about the genetics of human haemoglobin were developed largely through family studies of individuals with various abnormal haemoglobins; particularly noteworthy were the findings of Smith & Torbert (1958) who established the existence of individual α-and β-chain genes, most probably on separate chromosomes. Haemoglobin variants proved to be the products of alleles of either α- or β-chain genes, and Hbs F and A2 were shown to be due to the existence of separate γ- and δ-chain genes. The determination of the amino acid sequences established considerable homologies between the α, β, γ and δ-chains and it was suggested that these could be most simply accounted for by assuming that the genes which determine them were originally derived from a common ancestral gene. Successive duplications followed by separate evolution of the resulting genes by point mutations would then give rise to the different but related genes that exist today (Ingram 1961). The very close homology of the β- and δ-chains and the fact that the two genes lie close together on the same chromosome was taken as an indication that they have existed as separate entities only recently in evolutionary history.
Article
The effect of differences in G gamma and A gamma fractions of fetal hemoglobin (HbF) on the kinetics of polymerization of HbS-HbF mixtures was studied. We also examined their effect on oxygen affinity, surface hydrophobicity, mechanical stability, and solubility of HbF. Differences in G gamma:A gamma ratio did not affect the polymerization of mixtures of HbF and HbS, suggesting that the inhibitory effect of HbF on the polymerization of HbS is independent of the G gamma:A gamma ratio of HbF and is totally dependent on the fraction of HbF in the mixture. The oxygen equilibrium curve of HbF was not affected by differences in the ratios of G gamma and A gamma in HbF. In contrast, surface hydrophobicity, mechanical stability, and solubility of HbF were affected by differences in the G gamma:A gamma ratio. The higher the G gamma:A gamma ratio, the smaller the elution volume on a TSK Gel SW hydrophobic column in high phosphate buffer. The mechanical stability of HbF was also dependent on the ratio of G gamma:A gamma; stability was greater at higher fractions of A gamma. Differences in the G gamma:A gamma ratio also affected solubility of HbF: HbF containing the higher fraction of G gamma was the more soluble. These data indicate that although alanine at the 136th position of the gamma chains has a stronger surface hydrophobicity than does glycine, this difference does not affect either the polymerization of HbS or the oxygen affinity of HbF.
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A gel chromatographic analytical procedure using Bio-Gel A-0.5m in 6 m guanidine HCl-0.1 m 2-mercaptoethanol has been developed and standardized. The procedure permits the molecular weight of peptides in the size range of 2 to 146 amino acids in length to be established from the distribution coefficient of the peptide on the gel column. This procedure has been applied to an analysis of the size distribution of nascent peptides from rabbit reticulocyte ribosomes. These studies indicate that the size distribution of nascent peptides is nonuniform and that translation of hemoglobin messenger RNA molecules does not proceed at a constant rate in the reticulocyte.
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The γ chains of human fetal hemoglobin occur in both acetylated and nonacetylated state in vivo. The acetylated fetal hemoglobin F1 has been suggested to be α2γγacetyl (Biochim. Biophys. Acta, 63, 532 (1962)). The development of an electrophoretic assay capable of separating the α, β, γ, and γacetyl polypeptide chains in hemoglobins allowed us to show that highly purified hemoglobin F1 contained nearly equal quantities of α chains and a polypeptide chain migrating more slowly than the γ chain, and only trace quantities of γ chain. NH2-terminal and acetyl group analyses of globin prepared from hemoglobin F1 indicated the presence of 2 NH2-terminal valine residues, 0.4 NH2-terminal glycine residue, and 1.6 N-acetyl groups per mole of hemoglobin (molecular weight of 66,000). The acetylated polypeptide chain was isolated from carboxymethyl cellulose columns in the presence of 8 m urea and shown to have a blocked NH2 terminus, to contain 0.76 mole of N-acetyl residue per polypeptide chain (molecular weight of 16,500), and to migrate identically with the slow moving polypeptide chain of hemoglobin F1 in the electrophoretic assay. The acetylated NH2-terminal peptide was isolated from both F1 globin and the isolated γacetyl chain, and shown to be N-acetylglycylhistidine. This structure is consistent with the NH2-terminal sequence of the γ chain. These data indicate human fetal hemoglobin F1 should be designated α2γ2acetyl.
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The unstable hemoglobin (Hb) Saint Etienne (alpha2beta295F8 His replaced by G1n) (betaSE) was found in the red blood cells of an 8-year-old boy. The composition of this hemoglobin was 26% Saint Etienne, 52% A, 3% A2 and 19% HbF. Studies of hemoglobin synthesis indicate: a) a balanced synthesis of alpha and non-alpha chains (alpha=betaA + betaSE + gamma), b) an increased pool of free alpha hemoglobin chains, and c) a rapid exchange of alpha chains between this pool and HbSE. The alpha chain pool resulted from the dissociation of HbSE and the greater instability of betaSE chains than alpha chains upon heating. Hemoglobin F is of the fetal type and is heterogeneously distributed among the red cells. Furthermore, two populations of red blood cells could be separated according to their i antigen content. Analysis of the hemoglobins revealed a heterogeneous distribution. Thus, F hemoglobin was preferentially associated with cells having low i antigen level, while Saint Etienne hemoglobin was increased in cells having a high i antigen level. HbF and HbSE were not present in the parents of the propositus. Study of the genetic markers confirmed the filiation. The parents were normal upon clinical and hematological examination; they exhibited a normal pattern and synthesis of hemoglobin. The Hb Saint Etienne case is compared with Hb Istanbul, which in spite of the same amino acid substitution is not associated with increased HbF level.
Chapter
During the past two decades, significant advances have been made in our understanding of the human fetal and embryonic hemoglobins made possible by the availability of pure, highly characterized materials and novel methods, e.g., nano gel filtration, to study their properties and to correct some misconceptions. For example, whereas the structures of the human adult, fetal, and embryonic hemoglobins are very similar, it has generally been assumed that functional differences between them are due to primary sequence effects. However, more recent studies indicate that the strengths of the interactions between their subunits are very different leading to changes in their oxygen binding properties compared to adult hemoglobin. Fetal hemoglobin in the oxy conformation is a much stronger tetramer than adult hemoglobin and dissociates to dimers 70-times less than adult hemoglobin. This property may form the basis for its protective effect against malaria. A major source of the increased strength of fetal hemoglobin resides within the A-helix of its gamma subunit as demonstrated in studies with the hybrid hemoglobin Felix and related hybrids. Re-activating fetal hemoglobin synthesis in vivo is currently a major focus of clinical efforts designed to treat sickle cell anemia since it inhibits the aggregation of sickle hemoglobin. The mechanisms for both the increased oxygen affinity of fetal hemoglobin and its decreased response to DPG have been clarified. Acetylated fetal hemoglobin, which makes up 10–20% of total fetal hemoglobin, has a significantly weakened tetramer structure suggesting a similar role for other kinds of protein acetylation. Embryonic hemoglobins have the weakest tetramer and dimer structures. In general, the progressively increasing strength of the subunit interfaces of the hemoglobin family during development from the embryonic to the fetal and ultimately to the adult types correlates with their temporal appearance and disappearance in vivo, i.e., ontogeny.
Article
The effect of differences in G gamma and A gamma fractions of fetal hemoglobin (HbF) on the kinetics of polymerization of HbS-HbF mixtures was studied. We also examined their effect on oxygen affinity, surface hydrophobicity, mechanical stability, and solubility of HbF. Differences in G gamma:A gamma ratio did not affect the polymerization of mixtures of HbF and HbS, suggesting that the inhibitory effect of HbF on the polymerization of HbS is independent of the G gamma:A gamma ratio of HbF and is totally dependent on the fraction of HbF in the mixture. The oxygen equilibrium curve of HbF was not affected by differences in the ratios of G gamma and A gamma in HbF. In contrast, surface hydrophobicity, mechanical stability, and solubility of HbF were affected by differences in the G gamma:A gamma ratio. The higher the G gamma:A gamma ratio, the smaller the elution volume on a TSK Gel SW hydrophobic column in high phosphate buffer. The mechanical stability of HbF was also dependent on the ratio of G gamma:A gamma; stability was greater at higher fractions of A gamma. Differences in the G gamma:A gamma ratio also affected solubility of HbF: HbF containing the higher fraction of G gamma was the more soluble. These data indicate that although alanine at the 136th position of the gamma chains has a stronger surface hydrophobicity than does glycine, this difference does not affect either the polymerization of HbS or the oxygen affinity of HbF.
Article
DNA polymorphisms in the ε- and γ-globin gene regions in nine Asian macaques (Macaca fuscata, M. mulatta, M. nemestrina, M. cyclopis, M. fascicularis, M. arctoides, M. radiata, M. maura, and M. assamensis) were examined using several different restriction endonucleases and the human ε and γIVS2 probes. M. fuscata and M. mulatta had highly polymorphic sites (BglII and HincII, respectively) in the ε-globin gene region. The BamHI site in the γ-globin gene region was highly polymorphic in M. mulatta, while the BglII and HindIII sites in the γ-globin gene region were highly polymorphic in M. fuscata and M. mulatta. The presence of the γ-globin gene triplication was frequently observed in M. fuscata. The gain or loss of an additional BglII site between two γ-globin genes in Asian macaques seems to be very meaningful for discussing genetic relationships among them.
Chapter
Antibodies are proteins which are produced in vertebrates after stimulation with an antigen. They are specifically directed against the antigen which has caused their production.
Chapter
Innerhalb jeder Bevölkerung zeigen die Individuen eine außerordentlich bunte Vielfalt in ihren morphologischen und funktionellen Eigenschaften. Selbst Geschwister sind bezüglich Gestalt und Verhalten fast immer unverwechselbar verschieden. Verschiedene Bevölkerungen („Rassen“) unterscheiden sich in der Häufigkeit bestimmter Erbanlagen. Mit solchen Gruppenunterschieden, die vor allem Hautfarbe, Farbe und Form des Haares, Gesichtsform, Enzymvarianten, Blutgruppen und Serumgruppen, aber auch die Häufigkeit abnormer Merkmale, wie des Sichelzellhämoglobins, des Mangels an Glucose-6-Phosphat-Dehydrogenase und Mißbildungen wie Polydaktylie, Spaltbildungen des zentralen Nervensystems und Lippen-Kiefer-Gaumenspalten betreffen, befaßt sich neben der Humangenetik die Anthropologie.
Chapter
In Table 1 human enzymopathies, disorders in which a deficient activity of a specific enzyme have been demonstrated in man, are given. Synonyms are shown in parentheses. In cases where different enzymopathies result in a common phenotype the condition is enclosed in quotation marks (i.e. “adrenal hyperplasia”). An asterisk indicates enzymopathies in which the presumed enzyme deficiency has not been directly confirmed by enzyme assay. Table 1 is modified from McKusick (1971a) with additions and deletions.
Chapter
The permanent change in the morphological, biochemical, and functional characteristics of the red cell during development is a physiologic event the significance of which is not precisely known. The changes in different erythrocyte properties are not strongly correlated with each other or limited to the production processes of cells in the various hematopoietic sites. Among the criteria used to differentiate between fetal and adult erythrocytes, the shorter life span and the high susceptibility to oxidation stress do not imply that these cells are of inferior value. No data exist to suggest functional immaturity of fetal red cells under normal developmental conditions.
Chapter
Hämoglobin ist ein tetramerer Proteinkomplex, der aus 2 Globinkettenpaaren mit einem Molekulargewicht (MG) von zusammen 64400 besteht. Ein Globinkettentyp wird an der Spitze des kurzen Arms von Chromosom 16 kodiert, wo der a-Globin-Gen-Komplex mit den embryonalen Z- und den adulten a2- und a1-Genen lokalisiert ist. Der andere Typ wird auf dem kurzen Arm von Chromosom 11 im βS-Globin-Gen-Komplex mit dem embryonalen E-, den fetalen Gγ- und Aγ- und den adulten δ- und β-Globin-Ketten kodiert. Jede der 4 Untereinheiten ist kovalent an das Ferroprotoporphyrin Häm als Ligand gebunden. Die Struktur und die Funktion des Hämoglobins erlauben eine sehr gute Löslichkeit und Stabilität in den Erythrozyten, so daß die Aufnahme, der Transport und die Abgabe großer Mengen Sauerstoffs unter physiologischen Bedingungen ermöglicht werden.
Chapter
The biochemical and functional changes of red cells from fetal to adult characteristics are physiologic events of unknown significance. The developmental changes include membrane composition, structure, and pattern of hemoglobins; electrolyte concentrations; and red cell metabolism. An adult red cell and a fetal red cell differ in these respects. However, it is difficult to define exactly what a fetal cell is, since changes of the different properties (membrane, enzymes, and hemoglobin types) are not strongly correlated to each other or to functional changes. The most inadequate parameter for a definition is its content of fetal hemoglobin (H), since H-containing cells may also occur in or persist into adult life under different conditions, such as in hereditary persistence of fetal hemoglobin, or in hereditary or acquired hematological disorders. Moreover, erythrocytes in newborn infants containing the adult type of hemoglobin (H) may well have other functional and structural characteristics typical of a fetal cell. Related problems have been reviewed in more detail by Kleihauer (74).
Chapter
In the human fetus, beginning at 8 weeks of gestation, embryonic globins are gradually replaced by the α-globin chain and two (β-like chains, Gγ-globin and Aγ-globin, that differ only in presence of Gly or Ala at position 136 (Schroeder et al., 1968). α2γ2 is the predominant hemoglobin expressed during fetal life. Starting shortly before birth, the γ-globin chains are replaced gradually by the adult β- and δ-globin chains. Six months after birth, about 98% hemoglobin is α2β2. Besides the dramatic γ to β switch, a second switch, Gγ-globin to Aγ-globin, is observed postnatally, when the Gγ/Aγ-globin ratio declines progressively (Huisman et al., 1974; Comi et al. 1980). Synthesis of Gγ-, Aγ-, and β-globin can take place in a single erythroid colony (Terasawa et al., 1980; Comiet al., 1980; Peschle et al., 1980), raising the question, how switching is regulated.
Article
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Human bone marrow was pulse-labeled with radioactive amino acids for various times. Hemoglobin A after 3 min of pulse showed a sudden increase in the relative specific activities of peptides between position 90 and the COOH terminus in both the α and β chains. A control point in this region is postulated beyond which the growth of the polypeptide chains is markedly reduced, perhaps because of the assumption of a specific tertiary conformation of the growing chains after heme insertion. Pulse labeling of hemoglobin A2 indicates that δ chains are assembled at a rate much less than that for either α and β chains of hemoglobin A or α chains of hemoglobin A2. This can, in part, account for the small quantity of hemoglobin A2 with respect to hemoglobin A found in normal peripheral blood. Also, as cells age, their capacity to produce hemoglobin A2 is lost at a greater rate than their capacity to produce hemoglobin A. The assembly of α chains for both hemoglobins A and A2 proceeds at about the same rate, suggesting a common pool of α chains for the two hemoglobin types and their synthesis in the same cell.
Article
Horse haemoglobin contains up to four components which arise by substitution of glutamine for lysine at position alpha60 and of tyrosine for phenylalanine at position alpha24. The possible genetic reasons for this heterogeneity are discussed
Article
An abnormal fetal hemoglobin, designated hemoglobin FTexas, was found in the cord blood of five Negro infants (all related and three of them siblings) and of one Caucasian infant. Studies on the chemical structure of this variant indicate that there is a substitution of a lysyl residue for either the fifth or sixth glutamyl residue of the gamma-chain.
Article
Modifications of the Amino Acid Analyzer are presented which change the colorimeter cuvet configuration to allow for greater sensitivity as well as to provide increased resolution of the fractions eluted from the ion-exchange columns. Cuvet changes are combined with three different recorder modes—normal, expanded, and dual-range—which provide accurate analysis in concentration ranges of 0.020–0.600 μmole, 0.002–0.045 μmole, and 0.002–0.250 μmole, respectively.
Article
The synthesis of enzymes in bacteria follows a double genetic control. The socalled structural genes determine the molecular organization of the proteins. Other, functionally specialized, genetic determinants, called regulator and operator genes, control the rate of protein synthesis through the intermediacy of cytoplasmic components or repressors. The repressors can be either inactivated (induction) or activated (repression) by certain specific metabolites. This system of regulation appears to operate directly at the level of the synthesis by the gene of a shortlived intermediate, or messenger, which becomes associated with the ribosomes where protein synthesis takes place.
Article
The discovery of a variant of fetal hemoglobin in the cord blood of a Negro newborn is reported. The abnormal hemoglobin, designated as Hb-Warren, was studied by different analytic procedures, such as starch gel electrophoresis, anion exchange chromatography, ultraviolet spectral absorption, immunologic reactivity with various antisera, hybridization with canine hemoglobin and the determination of the total amino acid composition. It was concluded that Hb-Warren was composed of normal α-polypeptide chains and abnormal γ-polypeptide chains.
Article
Excerpt Transfer experiments in the reticulocyte ribosomal system using separate E. coli transfer RNAs for leucine indicated that one leucine position in the α-chain is different from all the other leucine positions in rabbit hemoglobin. In addition, the amino acid composition of the relevant peptides made us suspect that this leucine position might also be special in its structure (Weisblum, Gonano, von Ehrenstein, and Benzer, 1965). The experiments reported here were undertaken to determine the position of the exceptional leucine codon in the amino acid sequence of the α-chain. Evidence that this codon is in position 48 will be presented. As the studies on the amino acid sequence of the α-chain progressed, our suspicion was confirmed that position 48 was not only exceptional in its response to a minor leucine transfer RNA, but also, that leucine was not the only amino acid occupying that position. In the α-chain from a single...
Article
The sequences of amino acids in the α chains of hemoglobins from C57BL, BALB/c, and NB mice were studied. C57BL is a common strain of laboratory mice; therefore, it is used as the standard for comparison with others. The α chain of each has 141 amino acids and is homologous to that of man and other vertebrates. When these α chains were compared with that of normal adult human hemoglobin, amino acid exchanges were found at 16 positions. C57BL α chain differs from that of BALB/c at position 68 only, where C57BL consistently has asparagine while BALB/c apparently has two forms, differing only in whether there is serine or threonine inserted in the chain. The insertions of serine or threonine at position 68 occur at relatively equal frequencies. Several explanations for the production of two forms of α chains in BALB/c mice are presented. The α chain of NB hemoglobin shows three amino acid replacements when compared with that of C57BL: NB has valine rather than glycine at position 26, isoleucine rather than valine at position 62, and serine rather than asparagine at position 68.
Article
A modification of the anion exchange chromatography of various hemoglobin types using DEAE-Sephadex is presented. It has been observed that the replacement of the DEAE-Sephadex A-50, 100 to 270 mesh, by a similar preparation, but particle size 40 to 120 μ, greatly improved the resolution of several human and animal hemoglobin types.
Article
A fetal hemoglobin variant, designated hemoglobin FHouston, was found in the cord blood sample of a healthy, term Negro infant. The variant, comprising about 15 per cent of the total cord blood hemoglobin, diminished concomitantly with hemoglobin F, and it was barely detectable in the blood when the infant was 4 months old. The hemolysates of the parents and two siblings resolved into the usual adult pattern, but a trace amount of a fraction similar to hemoglobin FHouston was present in the father’s hemolysates and not in the mother’s. The ultraviolet absorption spectrum indicates that hemoglobin FHOUSTON contains γ polypeptide chains, and immunologic studies reveal the presence of both α and γ chains. In hybridization tests the alteration appears in the γ chain. Peptide chromatograms of hemoglobin FHouston indicated the presence of α and γ chains, but failed to reveal an abnormality. Amino acid analyses suggest that there may be a substitution of an alanyl for a glutamyl residue.
Article
Horse globin has been fractionated into two components by stepwise addition of acid acetone to an acidified globin solution and by gradient elution with urea from a carboxylic-type ion exchange resin at low pH.The components obtained by both methods are similar to those prepared earlier by electrophoresis. They have similar molecular weights (about 16,000) and appear to be present in nearly equal amounts. One has the N-terminal sequence valyl-leucyl- and the other valyl-glutamyl-. They differ electrokinetically and in other properties.
Article
A new type of abnormal fetal hemoglobin, identified in Rome from the cord blood hemolysate of a healthy newborn girl, is described. This abnormal hemoglobin, which the authors provisionally name Hb FRoma, has an electrophoretic mobility at alkaline pH identical to that of Hb Bart’s and a spectrum in the U. V. of the fetal type. It is, however, composed of normal alpha chains and altered gamma chains. Hb FRoma, which was present at birth in the portion of 17 per cent, disappeared completely during the 5th month of life. No abnormal hemoglobins were identified in the parents.
Article
The 146 amino acid residues of the γ chain of human fetal hemoglobin have been placed in sequence. The fetal hemoglobin for this investigation was isolated chromatographically from umbilical cord blood. The α and γ chains were separated prior to the determination of sequence. For the determination of the sequence, peptides were produced by individual hydrolyses with trypsin, chymotrypsin, or pepsin. The sequence of the individual peptides was determined largely through the application of the Edman degradation. The differences between the γ chains of human fetal hemoglobin and the β chains of human adult hemoglobin are responsible for the differences in the properties of the two molecules.
Article
Acceleration of analysis of amino acids by ion exchange chromatography has been facilitated in the Beckman amino acid analyzer by the use of a spherical particle resin. The acidic and neutral amino acids are analyzed on a 57- by 0.90-cm. resin column at a buffer volumetric input of 68 ml./hour (linear flow rate of 106 cm./hour). The basic amino acids are analyzed on a 5.0- by 0.90-cm. resin column at the same buffer flow rate. This system reduces the total analysis time to 4 hours, 5 minutes; (3 hours, 10 minutes for the acidic and neutral amino acids and 55 minutes for the basic amino acids). With the proper analysis sequence, three analyses can be completed in an 8-hour day.
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