Article

Non-protein nitrogenous constituents of rye grass: ionophoretic fractionation and isolation of a ‘bound amino-acid’ fraction

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... The occurrence of bound amino acids in plant leaves (Synge 1951;Synge and Wood 1958;Carnegie 1961) and the ability of bacteria to use some peptides more efficiently than free amino acids (Kihara and Snell 1960) makes inadequate a consideration of amino acid nutrition only in terms of the free amino acids required and those available. Direct assays of plant extracts have been made only with acid yield as an index of growth. ...
Article
Consideration is given to the adequacy of the free amino acids in plant juices at the time of harvest as nitrogen substrate for strains of lactic acid bacteria isolated from silage. The requirements of several strains of the bacteria for free amino acids in synthetic media were compared with the concentration of these acids in the liquid phase of plants at the time of harvest; this comparison suggested that several amino acids, and particulady lysine, may at times be rate.limiting. Ethanolic extracts of plants, sampled before and after a period of post-harvest wilting, were assayed as nitrogen substrates for the bacteria. A marked response to additions of lysine, some response to arginine, and evidence of deficiency of other acids were noted. The importance of post-harvest proteolysis to the amino acid nutrition of the bacteria in the silage environment is discussed. Certain fractions of the plant extracts were found to promote early growth of the bacteria in the synthetic medium, and the distribution of this activity in different fractions is described.
Chapter
Intermediate stages in protein synthesis and breakdownBound amino-acids in the fluids of living organismsSeparation of peptides from proteins: problems of defining the protein moleculeReferencesDiscussion
Article
The acid and alkaline hydrolysis of haddock actomyosin has been followed by the determination of free amino-acids and free amino groups. It was found that although amino-acid decomposition, like ammonia formation, is dependent on temperature, being greater at higher temperatures, the rate of peptide-bond hydrolysis is influenced more by alkali concentration than by temperature.
Article
The amino-acids of alcoholic extracts of lucerne hay cut in different stages of growth and mature grass and legume hays are estimated quantitatively by a rapid approximate paper chromatographic method. It is found that the amino-acids of the lucerne cut in varying stages of growth decline in quantity with increasing age, although some of the amino-acids form a fairly constant percentage of the total nitrogen at each stage. Differences in asparagine-aspartic acid content of lucerne hay from two different sources, as well as those of glycine, serine, alanine and proline, caused by manuring, are noted. Certain family amino-acid differences are observed among the mature hays. The alcoholic extracts of fenugreek seeds are found to contain few free amino-acids; other acids exist in peptide combination.
Article
The results of work conducted on the formation of volatile fatty acids in laboratory slurries of minced crop and water mixtures is presented. The absence of formic acid in such slurries has been noted. The occurrence of acids higher than C6, under varying conditions of temperature, aeration or anaerobiosis, has not been demonstrated. Straight-chain volatile acids from C1 to C8 have been shown to occur in field silage but only occasionally has the presence of branched-chain acids been noted. The principal volatile acid present is acetic acid.
Article
Italian ryegrass (Lolium multiflorum) S22, grown in Mg-deficient soil in pots, was given 40 and 160 mg N/kg of soil as ammonium nitrate or as ammonium sulphate treated with a nitrification inhibitor and 0, 20 and 40 mg Mg/kg of soil as magnesium sulphate. Yields of grass given the larger dressing of N were greater with ammonium nitrate than with ammonium sulphate. The magnesium treatments significantly increased yields only of the third cut given the most N when concentrations of Mg in dry matter were 0.07% or less. Magnesium fertiliser had little effect on the production of reducing sugars and sucrose but markedly increased fructosan and percentages of chlorophyll in grass of the third cut given the larger dressing of N. Non-protein nitrogen was much greater with ammonium sulphate than with ammonium nitrate nutrition. With both forms of N fertiliser, this fraction accumulated in grass grown without added Mg, but it decreased when Mg-deficiency was corrected. The percentage distribution of N in the free amino acid pool varied with the form of N fertiliser and the Mg treatments. With grass given ammonium nitrate, free amino acids predominated over amides; the reverse was true for grass given ammonium sulphate. The main effect of adding Mg was to decrease glutamine and to increase the percentages of some free amino acids, especially alanine and γ-aminobutyric acid. About half of the soluble organic N in grass given ammonium nitrate was unaccounted for as amino acids and amides with all the Mg treatments; this N fraction was much less in grass given ammonium sulphate, but it increased with increasing magnesium fertiliser.
Article
The redistribution of nitrogen which occurs during the wilting of immature ryegrass to moisture contents of 51% and 40%, and during its ensilage in air-tight containers at these moisture levels was measured. The extent of protein hydrolysis was less at the lower moisture level, and evidence was also gained that metabolism of the amino-acids released was less extensive in the drier samples. A passage of nitrogen into proline residues which occurred rapidly during wilting, did not proceed when the grass of low moisture content was stored anaerobically.
Article
Heavy application of fertiliser N caused a rise in the non-protein N content of the plant which was accompanied by a sharp rise in the free amino acid N, other organic nitrogenous constituents and nitrate N. The peptide N fraction of the plant was high when no nitrogen was applied, decreased with moderate supply of N and rose again slightly when heavy doses of N were applied. There was a steady increase in true-protein content with increase of N application; without N, accumulation of asparagine was noted. With a limited supply of N the dicarboxylic amino acids increased and also there was a considerable reduction of asparagine. Heavy fertilisation with N increased considerably the contents of asparagine and glutamine, the increase of glutamine being greater than that of asparagine, and was also accompanied by an increased content of all the amino acids.
Article
Italian ryegrass (Lolium multiflorum) S22, grown in a greenhouse in K-deficient soil in pots, was given 40, 80 and 160 mg of N/kg of soil (as ammonium nitrate) and 0, 60, 120 and 240 mg of K/kg of soil (as potassium chloride). In grass grown without added K, increasing N fertiliser increased the concentrations of total N, non-protein-N, ammonium-N, nitrate-N, free amino acids, amides and amines. With adequate K fertiliser all these N fractions decreased. The percentage distribution of N in the free amino-acid pool varied with the amount of N and K given. Without K fertiliser, increasing N had no consistent effect on most amino acids and amides, although it decreased the percentages of alanine and ethanolamine. Increasing K had relatively little effect on the percentage distribution in grass given the two smaller amounts of N. However, in the grass given the largest amount of N, it increased the percentage of most amino acids, especially alanine and 4-amino-n-butyric acid, and decreased glutamine and asparagine. β-Alanine was found only in K-deficient plants. The effect of K in relation to N metabolism and the nutritive value of herbage is briefly discussed.
Article
The total non-protein nitrogenous (NPN) fraction of oven-dried grassland herbage has been examined. The NPN was obtained by extraction of dried herbage with boiling water and it was fractionated as follows : (1) precipitation of part of the peptide-nitrogen with 75% alcohol, followed by (2) precipitation of purines with silver sulphate (this treatment also precipitated some peptides), followed by (3) passage through a cation-exchange resin, which gave three main fractions : (a) non-adsorbed nitrogen compounds, including nitrate, pyrimidines and unidentified substances, (b) adsorbed compounds which were eluted with sodium hydroxide—amino-acids, amides, ammonia, betaines, peptides or ‘bound’amino-acids, and unidentified substances and (c) basic compounds, including choline, and strongly adsorbed compounds that could not be eluted from the column with strong acid, probably mainly peptides and possibly including nucleotides. Two grasses, a clover and a lucerne sample were used and the proportion of their total nitrogen present as NPN varied from 23 to 30%. An analysis including amino-nitrogen after hydrolysis, amide-nitrogen, ammonia-nitrogen, nitrate-nitrogen, purine-nitrogen, betaine-nitrogen and choline-nitrogen accounted for 77-88% of the NPN. The fractionation gave higher recoveries when assumptions were made on the probable peptide content and it indicated where unidentified substances might be found.
Article
Free amino-acids were extracted from pasture plants with 80% alcohol, and the residue was extracted with water to remove bound amino-acids (peptide fraction). The alcohol extracts and the hydrolysed water-extracts were assayed microbiologically for 17 amino-acids. Total amino-nitrogen was also estimated in these extracts by Van Slyke's nitrous acid method. Most of the free amino-nitrogen was due to relatively few amino-acids, chiefly the dicarboxylic acids (and their amides), alanine and serine. A larger number of amino-acids contributed significantly to the peptide fraction. Treatment of the grasses with different nitrogenous fertilizers resulted in some differences in the amino-acid patterns. Larger differences were noted between young and more mature tissues. Of the total amino-nitrogen measured by Van Slyke's method about 70% in the free amino-acid fraction and about 95% in the peptide fraction were accounted for by assay of individual amino-acids.
Article
The proteins of broad-bean leaves and stems dissolved readily and almost completely in phenol-acetic acid-water (2: 1 : 1, w/v/v) provided preliminary treatments of the material which allowed the formation of insoluble complexes by chemical and physical interactions were avoided. The proportion of the total nitrogen extracted from growing tissue by the phenol-acetic acid-water mixture varied inversely with the nucleic acid content of the tissue, which decreased with increasing age of the plant. Strong electrolytes in low concentration markedly increased the solubility of the nucleic acids in phenol-acetic acid-water mixtures. A non-diffusible fraction, rich in hydroxyproline and soluble in cold trichloroacetic acid, was isolated. Hydroxyproline was also detected in the residue remaining after the phenol-acetic acid-water extractions. An unidentified compound giving a colour reaction with ninhydrin was also found in hydrolysates of the non-diffusible material extracted by cold trichloroacetic acid from semi-mature leaves.
Article
-Glutamyl-S-methylcysteine has been isolated from extracts of lima beans (Phaseolus lunatus L.). Two further peptides, -glutamyl-S-methylcysteine sulfoxide and -glutamyl-leucine have been tentatively identified. In addition, free S-methylcysteine was found in such extracts. The presence of these constituents in varying amounts was observed in all of 6 other varieties of beans that were investigated. During germination S-methylcysteine and all peptides occurring in lima beans are metabolized to unknown products. An oxidation-reduction function during the early phases of growth is suggested for the system: -glutamyl-S-methylcysteine/ -glutamyl-S-methylcysteine sulfoxide.
Article
An attempt has been made to account quantitatively for the main groups of chemical compounds in the dry matter of grasses. This was done by successive extractions with ethanol-benzene, warm water and ammonium oxalate solution, followed by digestion with pepsin and a delignifying treatment to isolate a holocellulose fraction. The polysaccharides in the holocellulose were determined. It was found possible to account for 97–98% of the grass dry matter and to identify all but 1–3% of it. The use to which such detailed knowledge can be put to provide a better assessment of the feeding value of grass is discussed.
Article
Two silages of contrasting protein content were compared in a 16-week winter-feeding experiment with 12 Ayrshire cows. One silage contained 8.2% DCP in its DM and the other 15.9% DCP. The silages were fed ad lib. with a supplement of either barley or barley plus groundnut cake. The DM digestibilities of the low and high protein silages were 74 and 67%, respectively, and the calculated S.E.s 56 and 47. Silage and total DM intakes were highest in the treatments containing low protein silage and in those containing groundnut. The mean daily milk yields for the treatments with and without groundnut were 35.4 and 32.s5 Ib (16.1 and 14.8 kg), respectively, with the high-protein silage, and 38.1 and 35.0 Ib (17.3 and 15.9 kg) with the low-protein silage. The S.N.F. contents of the milk were low and averaged 8.26 and 8.34% on the high- and low-protein silage treatments, respectively, and were not affected significantly by the supplements. It is concluded that the low-protein silage was superior to the high-protein silage as a feed for cows, and that the digestibility of the silage DM was a truer indication of quality than protein content.
Article
Amino acid concentrations in the peptide fraction of S22 ryegrass increased with total N content but when amino acid N was expressed as percentage of peptide N little variation was noted with increasing maturity or with increasing level of N application. Also under these conditions true protein increased but when expressed as a percentage of total protein N there was little change in the amino acid make-up of this fraction. Total dicarboxylic amino acid N and amide N maintained a 1 : 1 ratio in the peptide fractions under these conditions. Glycine and phenylalanine contents were relatively higher in the peptide fractions, and leucine and valine contents were relatively higher in the protein fractions. Proline content was unusually high in the free state, intermediate in the peptide fraction and lowest in the proteins. The amino acid make-up of the peptide fraction was more closely related to the protein fraction than to the free amino acid fraction and the free amino acids and their amides had some influence in determining the composition of the peptide fraction.
Article
The peptides of proline, methionine, phenylalanine and tyrosine, obtained by acid and enzymic hydrolysis of lysozyme, have been specially studied since the lysozyme molecule contains only 2, 2, 3 and 3 residues respectively of these amino acids. The linkages Lys·Val·Phe·Gly·Arg, Glu·Sér·Phe·Asp· and Ala·Lys·Phe·Glu, correspond to the three phenylalanine residues and the linkages Asp·Tyr·Arg·Gly, Arg·Gly·Tyr·Ileu·Leu and Asp(NH2)·Ala·Tyr·Gly·Ser·Leu·Asp(NH2) correspond to the three tyrosine residues. On the other hand, the two proline residues take part in the Thr·Pro and Leu·Pro bonds, while one of the methionine residues participates in the Ala·Ala·Met linkage. The specificity of chymotrypsine and pepsin is discussed in view of the results obtained.ZusammenfassungDie durch saure und enzymatische Hydrolyse des Lysozyms erhaltenen Peptide von Prolin Methionin, Phenylalanin und Tyrosin wurden besonders untersucht, da das Lysozymmolekül nur respective 2, 2, 3 und 3 Reste dieser Aminosäuren enthält. Den drei Phenylalaninresten entsprechen die Verknüpfungen Lys·Val·Phe·Gly·Arg, Glu·Ser·Phe·Asp und Ala·Lys·Phe·Glu, während den drei Tyrosinresten die folgenden Verknüpfungen entsprechen: Asp·Tyr·Arg·Gly, Arg·Gly·Tyr·Ileu·Leu und Asp(NH2)·Ala·Tyr·Gly·Ser·Leu·Asp(NH2). Andererseits nehmen die zwei Prolinreste an den Bindungen Thr·Pro und Leu·Pro teil, während einer der Methioninreste an der Verknüpfung Ala·Ala·Met beteiligt ist. Die Spezifität des Chymotrypsins und des Pepsins werden an Hand der erzielten Ergebnisse erörtert.
Chapter
Many of the foundations for the study of the proteins of plant tissues are to be found in the pioneer researches of H. Ritthausen (1862–1912) and of T.B. Osborne (1859–1929). The chief objective of this early work was the separation and purification of proteins from other plant constituents; Osborne (1924) in particular described methods for the preparation of protein from a wide variety of fruits and seeds and put forward a system for the classification of these reserve proteins which is still widely used. The separation of proteins from vegetative plant structures, such as leaves, was systematically investigated by Chibnall and his collaborators. As a result of this work, reviewed by Chibnall (1939), proteins associated with protoplasmic structures of the cytoplasm and chloroplast became accessible for investigation of their physicochemical properties and constituent amino-acids.
Chapter
The study of peptides in plants has been dominated by two aims. Most of the work described here has been carried out in order to identify some “active principle”, which has turned out to contain peptide bonds. Such “principles” may be active towards bacteria (e.g. gramicidin, penicillin, etc.), plants (e.g. lycomarasmin) or animals (e.g. the ergot alkaloids). The primary interest in much of this work has been to determine the structure of these physiologically active peptides; it is not generally known why they are active, nor the part they play in the metabolism of the organisms whence they originated. Chemically, these peptides are interesting in the variety of structures displayed and in the methods used to purify them and determine their structure; the use of these methods is a guide to the methods likely to be of promise in the purification and structure determination of proteins. Biologically, too, these physiologically active peptides serve as a reminder of the many possible complexities latent in the protein molecule. The second aim in the study of peptides is a more general one. Living cells commonly contain a score or so of amino-acids and many proteins, and the proteins themselves usually have at least 100 amino-acid residues in their molecules. Whether molecules of intermediate size are present (and if so, the part they play in protein metabolism) is an important, but largely unanswered, question. This section is written from the point of view that the main interest in the “active principle” type of work lies in the structure of the products, whereas the main interest at the moment in the second type of work lies in the analytical techniques. One of the most frequently used techniques is paper chromatography; its application to the study of the nitrogenous constituents of plants is described in a review by Steward and Thomson (1950).
Chapter
Despite many early reports of peptide-like compounds in plant tissues (for reviews of these early studies see, Bricas and Fromageot 1953, Synge 1959, 1968, Waley 1966), this class of compounds has received little attention in recent years. Indeed, the most recent review of the subject was published over 10 years ago (SYNGE 1968). The information pertaining to plant peptides is widely scattered in the literature and an exhaustive coverage will not be attempted here. Rather, a general survey will be made to illustrate the types of peptide found in plant tissues and to allow consideration of their possible functions. In addition, some speculations will be offered on possible roles which peptides might serve in plant cells, in the hope of stimulating greater consideration of this relatively neglected group of compounds.
Article
Short rotation ryegrass (Lolium sp.) and white clover (Trifolium repens) have been examined in some detail for the changes which take place in soluble non-protein-nitrogen fractions during wilting and ensilage. Similar studies have been made on subterranean clover (Trifolium subterraneum) and lucerne (Medicago sativa) undergoing ensilage.
Article
The amino acid. requirements of certain members of the viridans group of streptococci have been investigated. These requirements have not been found to be uniform among strains of StreptoooccUB bovis. Rumen strains of Strep. bows require, in addition to 20 amino acids, rumen liquor or an extract of rumen liquor or certain other organic complexes. The chemical nature of the active factor suggests a peptide . . The essential amino acids for the faecal strains of Strep. boviB were glutamic acid, aspartic acid, leucine, valine, asparagine, and histidine.
Article
Die mit 75% igem Alkohol extrahierbaren Aminosäuren und Amide aus 32, 50 und 64 Tage alten Knöllchen, knöllchenfreien Wurzeln und Blättern von Erbsenpflanzen wurden halbquantitativ papierchromatographisch bestimmt; ebenso nach Hydrolyse die Proteinaminosäuren der extrahierten Pflanzenrückstände. Vergleichend dazu wurden knöllchenfrei mit NO3- gezogene Erbsenpflanzen nach 20 und 40 Tagen ebenso untersucht. Zur Sicherung der halbquantitativen Werte wurden die Gesamt-α-Amino-N-Gehalte der Extrakte und Hydrolysate nach van Slyke bestimmt. Die Analysen werden auf Grund der Literatur besprochen und mit den Ergebnissen anderer Autoren verglichen. Die qualitative und quantitative Zusammensetzung der freien Aminosäurenfraktion wird als eine Stütze für die Meinung angesehen, daß der von den Knöllchenbakterien gebundene Stickstoff zunächst nicht durch Verdauung, sondern durch eine Abscheidung seitens der Bakterioiden für die Pflanze nutzbar wird.
Article
1. The free amino acid content of seeds Aberystwyth S. 143 cocksfoot (Dactylis glomerata L.), S.321 perennial ryegrass (Lolium perenne L.), S. 48 and S. 352 timothy varieties (Phleum pratense L.) was studied during ripening. 2. Floret samples were collected at 3 -day intervals and the total free amino acid levels determined by Formol titration. The content was found to be similar in all varieties, rising to a peak during the first phase of seed development, gradually decreasing to the point of harvest. 3. Two-dimensional chromatography indicated the presence of a total of sixteen ninhydrin-positive compounds, twelve being tentatively identified as specific amino acids. 4. Semi-quantitative estimations of each extract component were made, using a spot-area technique and all showed similar trends with respect to time. No individual amino acid was suitable for use as a ripeness indicator. 5. The basic similarity of the amino acid graphs with those presented in a previous paper dealing with soluble carbohydrates is discussed. It is concluded that the amino acid data support earlier harvesting of grass seed.
Article
Paper chromatograms of hydrolysates of 118 micro-organisms were examined in a study of the distribution of α, e-diaminopimelic acid and other amino-acids. A method for the identification of α, e-diaminopimelic acid is described. Diaminopimelic acid was found in nearly all the bacteria examined, except for the Gram-positive cocci, Streptomyces spp., and Actinomyces spp. It was also found in blue-green algae but in no other algae, nor in fungi, yeasts, plant viruses, or protozoa. Each species examined showed a different amino acid composition. β-Alanine and α- and γ-aminobutyric acids were sometimes found, often in several species of the same genus. Seven unidentified ninhydrin-reacting spots were recorded; none of them had the wide distribution of diaminopimelic acid.
Article
The principles, history, types, and applications of isoelectric focusing are presented. Also discussed are the theoretical aspects, electrooptical scanning, methodological parameters, and apparent physical constants. The lack of suitable carrier ampholytes is the primary reason why isoelectric focusing has not reached its full potential.
Article
WITH the object of correlating existing information and the possibility of establishing a relationship with taxonomy, we have examined, both qualitatively and quantitatively, the free and combined amino-acid content of the cell juices of a number of plants widely distributed throughout the vegetable kingdom, using a carefully worked-out paper chromatographic method. A complete account of the work will be published in due course; but in view of recent publications1 on the use of paper chromatography in the study of various aspects of the distribution and metabolism of amino-acids in plants, it appears to be desirable to place on record the results we have obtained during the past few years.
Article
SUMMARY : Toluene-treated washed suspensions of rumen bacteria break down proteins largely to amino acids ; in the absence of toluene bacterial deaminases are active. Unlike the deaminases, the presence of proteases does not depend, to any great extent, on the presence of readily attacked protein in the diet of the host animal. Extracts of acetone-dried powders of the bacteria also show proteolytic activity. Rumen protozoa are also proteolytic, and ammonia appears to be the end product of their nitrogen metabolism. Ammonia production due to the protozoa is not as sensitive to toluene as is the case with bacteria. Much of the ammonia production in the rumen in the absence of substrate appears to be due to the endogenous metabolism of the protozoa. Extracts of acetone powders, and extracts prepared by simple freezing and thawing of the protozoa, contain active proteases. In an artificial rumen apparatus it was shown that when digestion was complete, about half the N and C of added casein could be recovered as ammonia and volatile fatty acids respectively. Most of the remainder could not be accounted for analytic- ally, and was presumed to be used for microbial growth, which had occurred. When starch or some other polysaccharides were added to the artificial rumen apparatus as well as casein, the production of ammonia was lowered. This was shown not to be due to any effect on proteolysis or deamination, and was presumed to be due to the increased utilization for microbial growth of some breakdown product of casein. From at least the time of Zuntz (1891), it has been suspected that micro- organisms of the rumen split the proteins fed to the host animal; there has been, however, little unequivocal direct evidence for this proteolytic activity. Schlottke (1936) showed in vitro that glycerol extracts of rumen protozoa contained a protease active at pH c. 6.1, and also a dipeptidase, but was unable to find much activity in glycerol extracts of rumen bacteria. However, Sym (1938) showed active proteolysis at pH 6.3 by suspensions of rumen bacteria and of protozoa, and also by extracts of acetone powders of these micro- organisms; he found peptidase activity weak in his preparations. Both these authors found little or no free protease in the supernatant rumen liquor. Nikitin (1939) and Pearson & Smith (1943) demonstrated proteolysis by rumen micro-organisms in vitro. Indirect in vivo evidence that food protein is con- verted into microbial protein, with the presumption of intermediate proteo- lysis, was given by McDonald (1954) who reviewed the earlier evidence. The concentration of free amino acids in the rumen is at all times low (Chalmers & Synge, 1954b), but breakdown products of the amino acids, ammonia (McDonald, 1948, 1952) and volatile fatty acids (el-Shazly, 1952a) are found in high concentration when the diet of the animal contains adequate and suitable protein. Both the prior treatment and the nature of the protein affect the amount of breakdown products found. Chalmers, Cuthbertson &
Article
Two relatively new electrophoretic methods for the separation and characterization of proteins and other ion species, isoelectric focusing in natural pH gradients and isotachophoresis, are reviewed.
Article
Rumen bacteria were isolated from the rumen contents of eight Friesian cattle that had been fed a barley-soyabean diet. These preparations were freeze-dried, irradiated with 1 Mrad and analysed for various nitrogenous components. In nitrogen utilization studies involving both young and adult rats it was observed that the ‘true’ digestibility of the bacterial nitrogen was about 80%, while the net protein utilization (NPU) value was approximately 57. It was concluded that about 20% of the bacterial nitrogen, mainly incorporated in the cell wall, was not absorbed by the rat. On the other hand, about 71% of the absorbed nitrogen was utilized by the growing rat for tissue synthesis. Irradiation with 1 Mrad killed virtually all the rumen bacteria without adversely influencing the nutritional value of the bacterial protein.
Article
1. Ten successive trials with two Rahmany adult ewes were carried out with the aim of comparing the nutritive values of the nitrogenous constituents of some concentrates used in Egypt as supplements in summer rations (decorticated cottonseed cake, linseed-oil meal and beans ( Vicia faba )) and of animal proteins (meat meal, fish meal and casein) and of barseem ( Trifolium alexandrinum ). Wheat straw was employed as the main roughage in the ration. Nitrogen intake for all supplements was 10·16 g./day. 2. Apparent digestion coefficients for crude protein were estimated. Casein had the highest digestibility coefficient while meat meal was the least digestible. 3. Nitrogen retention and ruminal ammonia curves are given for each period. Only three proteins, namely, barseem, cottonseed cake and linseed meal gave positive nitrogen balance at the critical level of nitrogen intake used throughout the trials. Fish meal improved nitrogen retention significantly. Meat meal and beans did not improve nitrogen retention. The addition of 70 g. starch to beans improved nitrogen retention significantly.
Article
1. In a series of experiments with cannulated lambs the amounts of 2, 6-diaminopimelic acid (DAPA) and a-amino nitrogen passing daily through the abomasum, terminal ileum and rectum were measured. While there was a very significant net absorption of α-amino nitrogen between the abomasum and terminal ileum, there was no net absorption of DAPA between these points. Indeed, there was a tendency for more DAPA to leave the terminal ileum than entered the abomasum, though this was only significant at the 10% level. In all cases significantly less DAPA passed out of the rectum than passed through the terminal ileum, indicating extensive degradation of this amino acid in the hind-gut, probably as a result of microbial activity. 2. In adult sheep given control rations no DAPA could be detected in the blood, even when 643 ml plasma were analysed. These sheep usually excreted less than 5 mg DAPA daily in the urine. 3. When synthetic DAPA was introduced into the peritoneum, blood, abomasum, rumen or caecum of cannulated adult sheep in physiological amounts, approximately 80, 83, 53, 5 and 0 % of the administered dose was recovered in the urine. Furthermore, when introduced into the abomasum, DAPA could be measured in plasma from the anterior mesenteric and jugular veins. 4. It was concluded that in the normal sheep the DAPA-containing fraction of the bacterial cell-wall material synthesized in the rumen is not digested in the small intestine. In the caecum and colon, however, this fraction is extensively degraded by hindgut bacteria.
Article
The nitrogenous composition of the water soluble, non-protein nitrogen fractions of three samples of high-pH-spoilt silage and one sample of overheated silage were examined in detail. The amino acid nitrogen content of the high-pH-spoilt silages declined with increasing extent of spoilage, due to a selective degradation of the amino acids. Losses of amino acids were associated with proportionate increases in the amount of volatile basic nitrogen. Lower aliphatic amines were not present and it was therefore concluded that the ultimate end product of nitrogen metabolism in high-pH-spoilt silages was ammonia. Only low concentrations of putrefaction products, such as putroscine, cadaverine and histamine were present. The composition of the non-protein nitrogen fraction of the overheated silage was unusual in that the ammonia nitrogen content was high and associated with the complete destruction of certain amino acids. The free amino acid nitrogen content was low but this was partially compensated for by a very high ‘peptide’ nitrogen content. There was no evidence of putrefaction products in this silage.
Article
1. Three methods, based on treatment with neutral detergent or acid detergent, or involving ultrasonic disintegration, are described and compared for the direct estimation of undigested dietary nitrogen in individual samples of sheep faeces. Estimates of the true digestibility of the nitrogen in several sheep diets derived from analyses performed with these methods agreed well with each other, and were in accord with published estimates, derived by extrapolation techniques. Two other methods, based on treatment with phenol–acetic acid–water, and lysozyme–trypsin, respectively, were found to be unsuitable for such estimates. 2. The quantitative distribution of nitrogen between undigested dietary residues, bacterial residues, endogenous debris residues and the water soluble fraction was determined chemically. It was concluded that 57–81% of the non-dietary faecal nitrogen was associated with bacterial material. 3. Indirect evidence suggested that most of the bacterial nitrogen in faeces originated in the rumen.
Article
The nitrogenous composition of the water soluble fraction of maturing grass silage was investigated in detail. Empirical methods of group analysis demonstrated the complete absence of water soluble proteins, and that the major changes, involving the formation of amino acids and volatile amines, were completed within the first 2 months of ensiling. These methods were unable to account for a high proportion of the soluble nitrogen. Changes occurring within the soluble carbohydrate and volatile fatty acid fractions indicated that while secondary fermentations occurred some 8 months after ensiling they did not have any marked influence on the nitrogenous components. A detailed analysis of the individual components of the nitrogenous fraction was undertaken using both conventional methods of ion exchange chromatography and techniques developed especially for this purpose (see Hughes, 1969). Selective degradation of the amino acids liberated by the proteolysis of the grass proteins occurred. The volatile basic nitrogen content was comprised of ammonia. The non-volatile amine fraction, which accounted for a considerable proportion of the soluble nitrogen, was mainly composed of putrescine and cadaverine. There was no free histamine and only low concentrations of bound histamine were found. Evidence suggested that these amines were being further metabolized during the storage of the silage.
Article
Adaptation to pregnancy involves major changes in maternal metabolism to provide for the growing demands of the conceptus. Although changes in glucose metabolism, and possibly in fatty acid metabolism, occur in parallel with the increasing energy demands of the mother and the fetus, adaptation of protein metabolism appears to be in anticipation of maternal and fetal needs. During pregnancy, there is an excess of maternal nitrogen in the form of lean body mass over that deposited in the fetus and the products of conception; there is also a pregnancy-induced hypoaminoacidemia and a diminished amino acid response to protein intake, suggesting an increased uptake of amino acids in the splanchnic compartment. With the use of stable-isotope-labeled tracers, it was shown that there is a decreased rate of urea synthesis during pregnancy that is evident early in gestation. Kinetic studies of leucine metabolism showed no significant change in leucine carbon turnover but a significantly lower rate of leucine nitrogen turnover, suggesting a lower rate of leucine transamination. These data suggest an integral regulation of whole-body protein and nitrogen metabolism starting early in gestation and aimed at conservation and accretion of nitrogen by the mother and the fetus.
Article
MAILLARD1 was the first to record that solutions containing amino-acids and simple sugars turned brown on heating, and recently the additional observation was made2 that a mixture of D-galactose with certain amino-acids after treatment with alkali at 100° C. reacted with p-dimethylaminobenzaldehyde to give a purple colour. Further, the nitrogen-containing glycoside split off from ovomucin by the influenza virus enzyme was found3 to decompose rapidly with humin formation upon mild acid hydrolysis, whereas alkali treatment of the compound and addition of p-dimethylaminobenzaldehyde resulted in the formation of a stable purple colour. These observations prompted an investigation into the underlying chemical reactions.
  • W S Balaboucha-Popsowa
  • N J Gawrilow
  • A J Paradachwili
  • G F Jakounine
Balaboucha-Popsowa, W. S., Gawrilow, N. J., Paradachwili, A. J. & Jakounine, G. F. (1938). Bull. Soc. chim. Fr. [5], 6, 978.
  • H Theorell
  • A Akeson
Theorell, H. & Akeson, A. (1942). Ark. Kemi Min. Geol. 16A, no. 8.
  • H B Vickery
Vickery, H. B. (1924b). J. biol. Chem. 61, 117.
  • A H Gordon
  • A J P Martin
  • R L M Synge
Gordon, A. H., Martin, A. J. P. & Synge, R. L. M. (1941). Biochem. J. 85,1369.
  • T Ohira
Ohira, T. (1940a). J. agric. chem. Soc. Japan, 16, 1; Bull. agric. chem. Soc. Japan, 16, 10. Cited in Chem. Ab8tr. (1940), 34, 3683.
  • F C Steward
  • J F Thompson
  • C E Dent
Steward, F. C., Thompson, J. F. & Dent, C. E. (1949). Science, 110, 439.
  • H B Vickery
Vickery, H. B. (1925b). J. biol. Chem. 65, 657.
  • S M Partridge
  • H F Davis
Partridge, S. M. & Davis, H. F. (1950). Nature,Lond.,165, 62. Rees, M. W. (1946). Biochem. J. 40, 632.
  • H B Vickery
  • C S Leavenworth
Vickery, H. B. & Leavenworth, C. s. (1925). J. biol. Chem. 68, 579.
  • N I Gawrilow
  • A I Paradashvili
  • W S Balabouha-Popzova
  • S W Ljapounzowa
Gawrilow, N. I., Paradashvili, A. I., Balabouha-Popzova, W. S. & Ljapounzowa, S. W. (1938). Bull. Soc. chim. Fr. [5], 5, 973.
  • C E Dent
  • W Stepka
  • F C Steward
Dent, C. E., Stepka, W. & Steward, F. C. (1947). Nature, Lond., 160, 682.
  • R L M Synge
Synge, R. L. M. (1949). Quart. Rev. Chem. Soc. 8, 245.
  • H Beevers
Beevers, H. (1951). Biochem. J. 48, 132.
  • P Haas
  • T G Hill
  • B Russell-Wells
Haas,P., Hill, T. G. & Russell-Wells, B. (1938). Biochem. J. 82, 2129.
  • R H F Manske
  • A Neuberger
  • F Sanger
  • T Ohira
Manske, R. H. F. (1937). Canad. J. Res. 15B, 84. Neuberger, A. & Sanger, F. (1942). Biochem. J. 86, 662. Ohira, T. (1939). J. agric. chem. Soc. Japan, 15,370. Cited in Chem. Ab8tr. (1939), 38, 6245.
  • C H Lea
Lea, C. H. (1950). Chem. & Ind. p. 155.
  • A Allsopp
Allsopp, A. (1948). Nature, Lond., 1M, 833.
  • N I Gawrilow
  • W S Balabucha-Popzova
Gawrilow, N. I. & Balabucha-Popzova, W. S. (1934). Biochem. Z. 271, 292.