Biomedica biochimica acta (Biomed Biochim Acta)

Publisher: Akademie der Wissenschaften der DDR. Presidium; Deutsche Gesellschaft für Experimentelle Medizin

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Other titles Biomedica biochimica acta
ISSN 0232-766X
OCLC 9681158
Material type Periodical
Document type Journal / Magazine / Newspaper

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Hemorrhagic toxin e (Ht-e), a metalloproteinase isolated from the venom of the Western Diamondback rattlesnake Crotalus atrox, digests laminin and nidogen, both in their isolated forms and when present in a purified soluble complex. The only common site of cleavage by Ht-e of isolated nidogen and nidogen when complexed with laminin is at amino acid residue 336 in the amino terminal domain. Additionally, nidogen in complex with laminin is also cleaved at sites 322, 351 and 840 as determined by sequence analysis and site 953 as proposed from the molecular mass of a digestion product. Isolated nidogen, on the other hand, was cleaved at amino acid residues 75, 336, 402, and 920, as determined by sequence determinations and approximately at residues 296, 478, 625 and 702 as proposed from the molecular mass values of the generated polypeptide chains. Products from the proteolytic cleavage of the A and B2 chains of laminin were observed with the sites of cleavage determined to be at position 2666 in the laminin A chain and position 1238 in the laminin B2 chain. The laminin digestion products were identical regardless of whether nidogen was present in a complex with the laminin chains.
    Biomedica biochimica acta 02/1991; 50(4-6):763-8.
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    ABSTRACT: The ratio of hydrolysis to aminolysis product in papain-catalyzed acyl transfer reactions using various nucleophiles was determined. The data are interpreted in terms of binding specificity. The acyl transfer reactions were performed using the acyl donor Mal-Phe-Ala-OEtCl. The analysis of the structure-activity relationships of the hydrophobic S1'-P1' contact indicates that the S1' subsite can accommodate maximally three methyl(ene) groups. Hydrophilic amino acid side chains are better bound to S1' than can be explained by their hydrophobicities. The S2' as well as the S3' binding subsite exhibits a preference for space-filling hydrophobic amino acid residues.
    Biomedica biochimica acta 02/1991; 50(10-11):S122-6.
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    ABSTRACT: Autophagy is a non-selective bulk process for degradation of cytoplasm, as indicated by ultrastructural evidence and by the similarity in autophagic sequestration rates of various cytosolic enzymes with different half-lifes. The initial autophagic sequestration step is subject to feedback inhibition by amino acids, an effect which is potentiated by insulin and antagonized by glucagon. Epinephrine and other adrenergic agonists inhibit autophagic sequestration through a prazosin-sensitive, alpha 1-adrenergic mechanism. The sequestration is also inhibited by cAMP and by protein phosphorylation as indicated by the effects of cyclic nucleotide analogues, phosphodiesterase inhibitors and okadaic acid. Asparagine specifically inhibits autophagic-lysosomal fusion without having any significant effects on autophagic sequestration, intralysosomal degradation or on the endocytic pathway. Autophaged material that accumulates in prelysosomal vacuoles in the presence of asparagine is accessible to endocytosed enzymes, revealing the existence of an amphifunctional organelle, the amphisome. Evidence from several cell types suggests that endocytosis may be coupled to autophagy in a differential (ligand-dependent) manner, and that amphisomes may play a central role as collecting stations for material destined for lysosomal degradation.
    Biomedica biochimica acta 02/1991; 50(4-6):373-81.
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    ABSTRACT: Liver and intestinal nucleotides and energy charge levels were examined in rats at portal vein clamping for 1, 5 or 30 min and after reflow for 1 or 6 h following 30 min clamping. In both tissues, clamping resulted in a loss of ATP, energy charge, UTP, GTP, UDP-glucuronic acid and UDP-N-acetylhexosamine levels, which all, except ATP and total adenosine phosphates, essentially recovered at 1 h reflow. At 6 h reflow, liver UDP-glucuronic acid and liver glutathione decreased in both clamped and sham operated rats.
    Biomedica biochimica acta 02/1991; 50(8):1001-6.
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    ABSTRACT: Synthesis of LHRH N-terminal pentapeptide Glp1-His2-Trp3-Ser4-Tyr5-OMe (6) involving 3 + 2 enzymatic coupling has been developed. Synthetic strategy features the formation of one peptide bond (Glp-His) by chemical coupling and three peptide bonds by means of papain (Trp-Ser, Ser-Tyr) or alpha-chymotrypsin (His-Trp). High efficiency of this six-step synthesis is demonstrated by 44% overall yield. Its advantages are the use of inexpensive enzymes, simple isolation of intermediates and final pentapeptide, and easy recovery of substrates.
    Biomedica biochimica acta 02/1991; 50(10-11):S205-8.
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    ABSTRACT: Human cystatins A, B and C were purified, and their inhibition efficiency was tested with the cysteine proteinase cathepsin S. Cathepsin S was strongly inhibited by cystatins A and B in the subnanomolar range and by cystatin C in the picomolar range. Two steps of inhibition of cathepsin S by the cystatins which involve slow binding are discussed.
    Biomedica biochimica acta 02/1991; 50(4-6):631-5.
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    ABSTRACT: The ability of ascorbic acid (AA) (25 to 500 microM) to increase OH production by a chemical (Fe(2+)-EDTA-H2O2), an enzymatic (xanthine-xanthine oxidase-Fe(2+)-EDTA) and a cellular system (3.10(6) human polymorphonuclear leukocytes (PMNL) or murine peritoneal macrophages (PM) activated with 7.2 ng PMA/ml) was studied. At all concentrations used AA strongly enhanced OH generation by the chemical and the enzymatic systems. However, the maximal increase of about 14-fold was found for incomplete chemical system (10 microM Fe(2+)-20 microM EDTA) and 500 microM AA. In the case of phorbol-myristate-acetate-activated-PMNL and macrophages, the moderate increase in OH formation was only caused by low AA concentrations. At 50 microM AA, the OH formation was 112 +/- 3 and 117 +/- 4% of control, respectively. Higher AA concentrations had no influence or even decreased OH formation by phagocytes. It is suggested that administration of AA will not significantly enhance OH generation from pulmonary phagocytes and could be useful for prevention of the oxidant-mediated lung injury related to inflammation.
    Biomedica biochimica acta 02/1991; 50(3):265-72.
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    ABSTRACT: Calcium-phosphate induced fusion of human erythrocytes was investigated using an assay based on the relief of the fluorescence selfquenching of a fluorescent amphiphile incorporated into ghost membranes as it occurs when labeled membranes are fused with unlabeled membranes. Measuring ghost fusion up to Ca(2+)-concentrations of 4 mM in the presence of 10 mM phosphate, both an acceleration of the fusion process and an enhancement of the fusion extent with increasing amounts of calcium were observed. Fusion takes place even in the case when calcium-phosphate complexes were formed in the suspension medium prior to the addition of ghosts. These results are in contrast to previous observations, obtained by an internal aqueous content mixing assay, where fusion of ghosts was inhibited at Ca(2+)-concentrations greater than 1.75 mM, and preformed calcium-phosphate complexes were not able to induce fusion. The results point to the necessity of utilizing content mixing assays in conjunction with the lipid dilution assay to get a more detailed insight in membrane fusion mechanism(s).
    Biomedica biochimica acta 02/1991; 50(3):251-6.
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    ABSTRACT: In medical research and clinical practice, the increasing application of filtration measurements, to characterize the erythrocyte deformability has aroused an intensive discussion about possible erroneous interpretations of measured values (filterability indices). In the present paper the influence of white blood cells (WBC) on these indices is described and discussed in relation to a mathematical model of the filtration process. We found for two gravity filtration systems, using cellulose filters and concentrated erythrocytes suspensions sensitivities of their filterability indices of (1 +/- 0.1)% per 100 WBC/microliter (initial filtration rate measurement) and (3 +/- 0.3)% per 100 WBC/microliter (hemofiltrometer). In comparison to Nuclepore filtration systems with sensitivities of 5-12% per 100 WBC/microliters, cellulose filters were much less sensitive to WBC. The necessity, advantages and disadvantages of additional procedures for WBC removal are discussed. A standardization of residual WBC-count in limits of 500 +/- 300 WBC/microliters at a hematocrit of 60% is proposed. Fitting of the filtration curves of the hemofiltrometer to a model function may either improve the accuracy of estimation of filterability indices or divide them into two model parameters with different WBC-sensitivities: the initial filtration rate parameter having a low WBC-sensitivity ((0.9 +/- 0.2)% per 100 WBC/microliter) and the occlusion related parameter having a 12 times higher sensitivity ((11 +/- 1)% per 100 WBC/microliter). Interpretation, advantages and disadvantages of the model parameters are discussed also in comparison to the filterability index.
    Biomedica biochimica acta 02/1991; 50(2):159-68.
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    ABSTRACT: Various polymeric oxidation products of polyphenols strongly inhibited the purified lipoxygenase of rabbit reticulocytes, whereas the prostaglandin H synthase of sheep vesicular gland was only weakly inhibited. The oxidized polymeric preparations of caffeic acid, 2,5-dihydroxytoluene and 3,4-dihydroxytoluene were the most potent lipoxygenase inhibitors. Since such preparations are also known to inhibit herpes simplex virus in an early stage of the virus-cell interaction it is proposed that lipoxygenase metabolites are involved in virus-induced changes in the cell metabolism.
    Biomedica biochimica acta 02/1991; 50(3):299-305.

  • Biomedica biochimica acta 02/1991; 50(4-6):413-20.
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    ABSTRACT: L-ornithine has growth potential for parenteral nutrition and as a component for biologically active peptides. A process for enzymatic conversion of L-arginine to L-ornithine with arginase has been developed and tested on a pilot scale. With activation of arginase by Mn2+ and stabilization by ascorbic acid, the enzyme is sufficiently active and stable for application in large-scale L-ornithine synthesis.
    Biomedica biochimica acta 02/1991; 50(10-11):S249-55.
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    ABSTRACT: A synthetic master gene coding for rat trypstatin was designed, assembled of eight oligonucleotides, ligated into the cloning vector pUC8 and cloned in E. coli. In addition to the expected product DNA sequencing revealed the presence of several gene variants. The gene coding for (-1M F44G) rat trypstatin was mutated to a wild type form (-1M) rat trypstatin by cassette mutagenesis. For the first expression experiments the E. coli pEx31 system was used. After SDS-PAGE analysis fusion proteins were detected consisting of the N-terminal part of MS2-polymerase, a linker region and of the appropriate rat trypstatin variant. These fusion proteins were synthesized in amounts as high as 25% of total E. coli proteins.
    Biomedica biochimica acta 02/1991; 50(4-6):701-5.
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    ABSTRACT: Kinetics of penicillin acylase-catalyzed acyl group transfer to amino acids, their esters and peptides have been analyzed. The synthesized product accumulation curves have clearly expressed a maximum. Amino acids with non-branched side chain alkyl radicals were demonstrated to be effective nucleophiles, with glycine, L-phenylalanine and L-phenylglycine being the best. D-amino acids were shown to possess much lower reactivity. Practically for all L-amino acids and peptides tested, the yield of their N-phenylacetyl derivatives in the course of penicillin acylase-catalyzed acyl group transfer reactions was found to be more than 50%. Optimization of such enzymatic synthesis required to increase its potential on the preparative scale.
    Biomedica biochimica acta 02/1991; 50(10-11):S237-42.
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    ABSTRACT: In human, goat and chick amniotic fluid the contents of lecithin, lysolecithin and phosphatidyl ethanolamine increase during embryonic development. The sphingomyelin content however, increased during the early period only and declined during the latter part of development.
    Biomedica biochimica acta 02/1991; 50(8):955-8.
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    ABSTRACT: Calf chymosin catalyzes peptide synthesis optimally at pH 4-5 giving satisfactory yields of methyl esters or p-nitroanilides of benzyloxycarbonyl tetra- to hexapeptides, provided that hydrophobic amino acid residues form the new peptide bond. The enzyme efficiency depends also on the nature of adjacent amino acid residues. As an aspartyl proteinase with characteristic specificity pattern chymosin would be useful for synthesis of middle length peptides.
    Biomedica biochimica acta 02/1991; 50(10-11):S102-5.
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    ABSTRACT: Dichloromethane sensitizes the myocardium to arrhythmia development in response to catecholamines. The effects of acute dichloromethane exposure (3.1, 6.2 or 12.4 mmol/kg) on cardiovascular actions of epinephrine (1 or 4 micrograms/kg iv) and norepinephrine (2 or 10 micrograms/kg iv) in the urethane-anaesthetized rat model was investigated. Hypertensive epinephrine effects as well as reflex bradycardia after epinephrine and norepinephrine injections were augmented in dichloromethane-exposed rats. Moreover we observed an enhanced negative dromotropic epinephrine action. The transient T-wave elevation after catecholamine injection was markedly increased in animals treated with 12.4 mmol/kg dichloromethane. The results show that dichloromethane exposure modifies cardiovascular actions after catecholamine administration. The release by dichloromethane of endogenous catecholamines could play a role in the manifestation of these effects.
    Biomedica biochimica acta 02/1991; 50(3):307-11.
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    ABSTRACT: DL-omega-phenyl amino acid esters turned out to be inhibitors of the sheep vesicular gland prostaglandin H synthase in addition to their antiphlogistic action on the carrageenan-induced oedema of the rat paw and weak antihistaminic actions. The inhibition of the prostaglandin H synthase was dose-dependent, the inhibitory potencies were however much lower than that of indomethacin. Some but not all derivatives, such as DL-4-amino-4-phenylbutyric acid octyl ester, also caused inhibition of the pure lipoxygenase from rabbit reticulocytes and the conversion of arachidonic acid to leukotriene B4 and 5S-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid by human polymorphonuclear leukocytes as well as inhibition of antigen-induced release of histamine from mast cells of ovalbumin-sensibilized rats. Since no clear relations between the data of the in vitro and in vivo models were obtained, further studies on the pharmacokinetics and possible biotransformations are required.
    Biomedica biochimica acta 02/1991; 50(2):189-98.

  • Biomedica biochimica acta 02/1991; 50(10-11):S193-6.

  • Biomedica biochimica acta 02/1991; 50(10-11):S127-30.