A study of the interaction of glycine and its oligohomopeptides with formaldehyde and acetaldehyde under possible primitive earth conditions

It is established that glycine and glycine oligohomopeptides interact with formaldehyde and acetaldehyde in a homogeneous weak acid medium (pH 3.3–3.7) at mild temperatures (60–80°C) in the absence of inorganic solid substances. Together with the expected serine and threonine, the formation of alanine, glutamic and aspartic acid, norvaline and isoleucine, as well as four non-protein amino acids is also established. It is suggested that the non-protein amino acids are hydroxymethylserine, hydroxymethylthreonine, hydroxymethylaspartic acid and γ-amino-δ-hydroxyvaleric acid. The modes of formation of all protein and non-protein amino acids are discussed. These results strengthen the probability that similar processes may have been one of the pathways for the prebiotic synthesis of amino acids on primitive Earth.     

Contents of amino acids in Tricholoma giganteum

Seventeen protein-constitutive and free amino acids were isolated and determined from the fruit-bodies of Tricholoma giganteum . Aspartic acid and alanine were the most abundant protein constitutive amino acids. Among the free amino acids, alanine, glutamic acid, serine, aspartic acid and glycine were present in the largest amounts, with aspartic acid and glutamic acids especially dominant.     

Amino-acid synthesis in adult Dacus oleae (Gmelin) (Diptera Tephritidae) determined with [U-14C] glucose

The ability of adult Dacus oleae for amino-acid synthesis from [U-14C] glucose was investigated. The relatively high specific activity radiometric measurements indicated that both sexes were able to synthesize the amino acids: alanine, aspartic acid, cystine, glutamic acid, glycine, hydroxyproline, proline and tyrosine; therefore, these amino acids are considered as nutritionally dispensable for D. oleae. On the other hand, the amino acids: arginine, histidine, leucine, isoleucine, lysine, methionine, phenylalanine, serine, threonine, and valine, showed a very low specific activity and therefore are considered as nutritionally indispensable. It was not possible to conclude about tryptophane, since the acid hydrolysis destroyed this amino acid.     

Free Amino Acids in Serine-Antagonized Cells of Tetrahymena pyriformis.

Wragg, June B. (Agricultural Research Service, Beltsville, Md.), Howard Reynolds, and Michael J. Pelczar, Jr. Free amino acids in serine-antagonized cells of Tetrahymena pyriformis. J. Bacteriol. 90:748-754. 1965.-Growth inhibition of Tetrahymena pyriformis by l-serine in a chemically defined medium was reversed by l-arginine in a manner which resembled competitive antagonism. Composition of the free amino acid pools from cells grown in either a balanced amino acid mixture or a mixture with serine concentrations which inhibited growth suggested an antagonism by serine with energy-yielding reactions. Growth in media with excess serine resulted in the accumulation of higher concentrations of free cellular amino acids and an apparent increase in the rate of conversion of arginine to ornithine, as compared with growth in the balanced medium. The results suggested that serine or a metabolic product of serine interferes with the formation of pyruvic acid. In the presence of high levels of serine, arginine appeared to be metabolized more rapidly and to be spared when alanine, aspartic acid, or glutamic acid was added to the unbalanced medium.     

Genetic code: codon bases--the symbols of amino acid synthesis and catabolism pathways

The correlations between genetic codes of amino acids and pathways of synthesis and catabolism of carbon backbone of amino acids are considered. Codes of amino acids which are synthesized from oxoacids of glycolysis, the Krebs cycle and glyoxalic cycle via transamination without any additional chemical reactions, are initiated with guanine (alanine, glutamic and aspartic acids, glycine). Codons of amino acids which are formed on the branches of glycolysis at the level of compounds with three carbon atoms, begin with uracil (phenylalanine, serine, leucine, tyrosine, cysteine, tryptophan). Codes of amino acids formed from aspartate begin with adenine (methionine, isoleucine, threonine, asparagine, lysine, serine), while those of the amino acids formed from the compounds with five carbon atoms (glutamic acid and phosphoribosyl pyrophosphate) begin with cytosine (arginine, proline, glutamine, histidine). The second letter of codons is linked to catabolic pathways of amino acids: most of amino acids entering glycolysis and the Krebs cycle through even-numbered carbon compounds, have adenine and uracil at the second position of codes (A-U type); most of amino acids entering the glycolysis and the Krebs cycle via odd-numbered carbon compounds, have codons with guanine and cytidine at the second position (G-C type). The usage of purine and pyrimidine as the third letter of weak codones in most of amino acids is linked to the enthropy of amino acid formation. A hypothesis claiming that the linear genetic code was assembled from the purine and pyrimidine derivatives which have acted as participants of primitive control of amino acid synthesis and catabolism, is suggested.     

Free alanine,aspartic acid,or glutamic acid reduce the glycation of human lens proteins

The amino acids lysine and glycine are reported to react with glucose at physiological pH and temperature and undergo non-enzymic glycation. Three other amino acids present in relatively larger amounts in the lens i.e. alanine, aspartic acid and glutamic acid were also found to undergo non-enzymic glycation as found by incorporation of uniformly labelled (U-[¹⁴C]) glucose into the amino acids. The glucose incorporation was 1.6 to 2.5% for alanine, 35 to 50% for aspartic acid and 2.3 to 3.3% for glutamic acid. Each amino acid of varying concentrations lowered the extent ofin vitro glycation of lens proteins significantly in glucose-treated homogenates of normal lens from humans. The decrease in glycation for alanine was between 32 and 69%, that for aspartate was between 18 and 74%, and for glutamate was between 52 to 74%. Decreased glycation was greater for higher concentrations of glucose. Scavenging of intracellular glucose and decreasing the extent of glycation of lens proteins could be the mechanism of action by which the amino acids alanine, aspartic acid and glutamic acid could exercise a beneficial effect on cataract and diabetic retinopathy.     

E.s.r. of spin-trapped radicals in aqueous solutions of amino acids. Reactions of the hydroxyl radical.

The radicals produced by reactions of hydroxyl radicals with amino acids in aqueous solutions have been investigated. Hydroxyl radicals were formed by U.V.-photolysis of hydrogen peroxide and the short-lived amino acid radicals were spin-trapped by tert-nitrosobutane and identified by electron spin resonance spectroscopy. Nineteen amino acids were studied, and several radicals were identified which have not been observed previously by other methods. Only side-chain radicals were identified for alanine, threonine, aspartic acid, asparagine, lysine, phenylalanine, tyrosine, proline and hydroxyproline; whereas for glycine the C(2) carbon radical was spin-trapped. Both C(2) carbon radicals and side-chain radicals were assigned to valine, leucine, isoleucine, serine, glutamic acid, glutamine, arginine and methionine.     

End products of glucose and glutamine metabolism by L929 cells

Products of glucose and glutamine metabolism by L929 cells were detected and quantitated by gas chromatography and mass spectrometry of the oxime-trimethylsilyl derivatives. This method allowed detection and identification of all major carboxylic and amino acids produced in the system. Although lactic acid was expected to be the major product, alanine, citric, glutamic, aspartic, and pyruvic acids were also released into the culture medium at significant rates. Incorporation of labeled carbon from D-[U-13C]glucose showed that the alanine, lactic, and pyruvic acids were derived from glucose as was one-third of the citric acid carbon. The rate of glucose utilization for production of these end products was 29-fold greater than the rate of glucose oxidation to CO2, and calculated ATP production from alanine and pyruvate synthesis exceeded that from lactate synthesis by nearly 2-fold. Utilization of glutamine for synthesis of aspartic, glutamic, and citric acids also exceeded the rate of glutamine oxidation, thereby making end-product synthesis from glucose and glutamine the dominant cellular metabolic activity. In the absence of glucose, synthesis and intracellular levels of aspartic and glutamic acids increased, whereas synthesis and cell content of the other acids decreased markedly. This response is consistent with the metabolic pattern proposed by Moreadith and Lehninger (Moreadith, R.W., and Lehninger, A.L. (1984) J. Biol. Chem. 259, 6215-6221) in which much of the glutamine used by these cells is converted to aspartate in the absence of a pyruvate source and to aspartate or citrate in the presence of pyruvate.     

The Mechanism of Acetate and Pyruvate Oxidation by Trypanosoma cruzi

The epimastigote or culture form of Trypanosoma cruzi oxidizes [3-¹⁴C] pyruvate and [2-¹⁴C] acetate to ¹⁴CO₂ without an apparent increase in overall respiration. This oxidation takes place through the tricarboxylic acid cycle as shown by (a) the incorporation of substrate ¹⁴C into cycle intermediates; (b) the earlier liberation of acetate carboxyl carbon as CO₂; and (c) the characteristic intramolecular distribution of pyruvate and acetate carbon atoms in the skeletal carbon of aspartic and glutamic acids. Upon oxidation of [3-¹⁴C] pyruvate and [2-¹⁴C] acetate, two of the products, alanine and glutamic acid, are found to account for more than 50% of incorporated ¹⁴C; labeling of alanine predominates with [3-¹⁴C] pyruvate while labeling of glutamic acid predominates with [2-¹⁴C] acetate. Using [1- or 6-¹⁴C] glucose as substrate, the pattern of ¹⁴C distribution in soluble metabolites closely resembles that obtained with [3-¹⁴C] pyruvate, in accordance with the joint operation of the Embden-Meyerhof pathway and Krebs cycle. The cycle operation depends on electron transport through the mitochondrial respiratory chain, since antimycin A, at a relatively low concentration, inhibits the oxidation of [2-¹⁴C] acetate to ¹⁴CO₂, to the same extent as the parasite respiration. Though functional in T. cruzi epimastigotes, the oxidative role of the Krebs’ cycle is apparently limited by the absence of an efficient oxidative apparatus. The cycle operation does, however, constitute an important source of skeletal carbon for the biosynthesis of amino acids and can contribute to the process of glycogenesis.     

Biosynthesis of amino acids from sucrose and Krebs cycle metabolites by Rhizobium lupini bacteroids

Summary The possibility of amino acids biosynthesis from sucrose, metabolites of Krebs cycle or glyoxylate and ammonium by intact bacteroids has been studied. The suspension of intact Rhizobium lupini bacteroids in phosphate buffer solution pH 7.8 was shown to catalyse the biosynthesis from sucrose and ammonium of some amino acids, such as alanine, aspartic and glutamic acids, glycine and serine. The yield of alanine and aspartic acid was 2.5–3 times higher than that of other amino acids, which were formed in almost equal quantities. Intact bacteroids were also found to catalyse the biosynthesis of aspartic and glutamic acids, alanine and glycine from ammonium and Krebs cycle metabolites such as fumaric acid (FA), oxaloacetic acid (OAA), pyruvic acid (PA), a-ketoglutaric acid (a-KGA), malic acid (MA), as well as from glyoxylic acid (GOA). The biosynthesis of aspartic acid from fumaric acid was dominant. Besides that, the suspension of intact bacteroids catalysed transamination of aspartic and glutamic acids, the transamination of aspartic acid being especially intense with -KGA and GOA. Aspartic acid was synthesized most efficiently through the amination of fumaric acid, while glutamic acid was better synthesized through the transamination of aspartic acid with -KGA than through reductive amination of -KGA.The experimental data proved that intact bacteroids posess Krebs cycle enzymes and primary ammonia assimilation enzymes. This enzyme complex permits bacteroids to detoxify ammonia, which they produce using sucrose and metabolites of Krebs cycle as the sources of carbon.The data obtained are of great interest as they prove the importance of bacteroids in the synthesis of amino acids from ammonium which is formed in the course of N₂-fixation, and sucrose available from leaves.     

Aspects of amino acid metabolism and nutrition in the ectoparasitoid wasp, Exeristes roborator

Exeristes roborator contains a wide variety of free amino acids, and the composition of all developmental stages was quantitatively dominated by proline and glutamic acid. The latter occurred together with lesser amounts of glycine, alanine, valine, leucine, tyrosine, and histidine which varied between developmental stages. Minor and trace amounts of most other commonly occurring amino acids were also found. The percentages or relative amounts of major constituents were not influenced when the parasite was reared on the alternate hosts, Pectinophora gossypiella and Gnorimoschema operculella. Likewise, the major characteristics of the latter hosts' free amino compositions could not be accounted for, in either case, by their diets.Differences in the relative distribution of the major amino acids between the developmental stages of E. roborator indicate large decreases in the percentage of proline occur during development from the larval to the adult stage with corresponding increases in the percentages of glycine in the pupal stage and alanine as well as other amino acids in the adult stage. The results suggest that proline may play an important rôle in E. roborator, probably as an energy reserve.The amino acid compositions of the total proteins of E. roborator and its hosts were similar and all quantitatively dominated by glutamic acid, aspartic acid, and amides. However, the disk gel electropherograms of the proteins of both hosts and parasite were different. Quantitative changes were evident in the protein pattern of the parasite when reared on the alternate hosts.E. roborator incorporated radioactivity from ¹⁴C(U)-glucose into the amino acids, glutamic acid, aspartic acid, serine, glycine, alanine, and proline. Furthermore, ¹⁴C(U)-glutamic acid was incorporated into a wide variety of proteins. The data suggest that the above amino acids may be non-essential dietary components for E. roborator. However, quantitative determinations indicate that the amount of glutamic acid synthesized does not account for the amount incorporated into protein over the same time period.     

Correlation between [U-14C]glucose metabolism and function in perfused cat brain

In brain perfusion experiments conducted with blood containing [U-14C]glucose the relative specific activity (RSA) of blood glucose carbon incorporated in brain intermediate metabolites was measured. It was demonstrated that the so-called metabolic pattern of Geiger is not constant, but it bears a close relation to the function of the brain. The results of the study may be summarized briefly as follows. (1) In a group (A) of cats with a high level of brain function, the RSA of lactic acid was 75 per cent; that of glutamic acid 80 per cent; aspartic acid 75 per cent; glutamine 61 per cent; GABA 43 per cent; and respiratory CO2 55 per cent. It was observed that the major part of the carbon of amino acids, such as glutamic acid and aspartic acid, which are directly associated with the tricarboxylic acid cycle are derived from blood glucose. (2) In a group (B) showing a low level of brain function, the RSA of each amino acid was considerably lowered. The RSA of glutamic acid and aspartic acid was about 50 per cent and that of respiratory CO2 was 27 per cent. (3) In a group (C) with a still lower level of brain function, each amino acid as well as the respiratory CO2 had still lower RSA values. (4) The metabolic pattern of Geiger corresponds to values obtained during low functional activity of the brain in our experiment.     

Synthesis of proteins and nucleic acids by the pea aphid Acyrthosiphon pisum (aphididae) in the absence of a full complement of dietary amino acids

Protein, nucleic acids, and nucleotide syntheses were studied in pea aphids, Acyrthosiphon pisum (Harris), by feeding them labeled ¹⁴C-amino acids and [5-³H]-orotic acid in sucrose. It was demonstrated that in the absence of dietary essential amino acids, aphids were capable of synthesizing nucleic acids, nucleotides, and proteins when provided with a single dietary amino acid in sucrose. It is suggested that other required amino acids were possibly supplied by the symbionts present in the pea aphid and/or were obtained from the amino acid pool in the hemolymph or glucose, one of the end products of sucrose digestion. Of the various amino acids tested, synthesis of measurable amounts of protein or other compounds occurred when alanine, aspartic acid, glutamic acid, glycine, proline, or serine were provided, but no synthesis occurred with cysteine.     

Quantitative analysis of free amino acids and carbohydrates in spring barley anthers at different stages of maturity

The content of the carbohydrates glucose, fructose and sucrose was determined in spring barley anthers at different stages of maturity. During maturation the sucrose content of the anthers increased markedly. The following 17 free amino acids were detected in anthers of different stages of maturity: aspartic acid, glutamic acid, serine, alanine, arginine, leucine, isoleucine, lysine, α-aminobutyric acid, glutamine, proline, tyrosine, phenylalanine, valine, threonine, cystine and glycine. Quantitative analysis was only carried out in amino acids present in higher concentrations in the analysed samples. These were: aspartic acid, glutamic acid, α-aminobutyric acid, proline, serine, valine and glutamine, and a mixture of amino acids (leucine, isoleucine, valine and phenylalanine). The total content of free amino acids increased with increasing maturity of the anthers. However, not all amino acids followed contributed to this increase, but only proline, glutamic acid, aspartic acid and glutamine. A small difference was found in the variety Gopal in which the aspartic acid content did not increase significantly, but the content of the mixture of amino acids and serine did. With the exception of green anthers of the variety Firlbecks Union, proline was present in the highest concentration in all samples analysed.     

Amino acid utilization by L-M strain mouse cells in a chemically defined medium

Summary The amino acid requirements of strain L-M mouse cells grown in a chemically defined medium (2×Eagle) containing only the 13 essential amino acids (EAA) were investigated. Medium and acid hydrolysate samples were analyzed for amino acid content by the method of ion exchange chromatography. The extent of utilization of the EAA differed;e.g. after 120 hr of cell growth without medium change, glutamine was exhausted from the medium; methionine, leucine, isoleucine, cystine, arginine, and valine were depleted 60 to 80%; other EAA were used to lesser extents. Although the EAA were used in excess of their requirements for protein synthesis, a correlation could generally be made between utilization and protein amino acid composition. Glutamine appeared to be, a growth-limiting factor. Use of U-¹⁴C-labeled glutamine indicated that over one-half of the metabolized glutamine was converted to carbon dioxide, 17% to cell material, and 15% was extracted from the amino acid pools. Nonessential amino acids (NEAA), viz. alanine, aspartic acid, glutamic acid, glycine, proline, and serine, were released into the medium during growth, and some were reutilized. Exogenous provision of these did not improve cell growth. In contrast to the other NEAA, only serine showed net utilization when provided exogenously. When glutamic acid largely replaced the glutamine in the medium, it exerted a sparing effect on the glutamine requirement for protein synthesis. Suggestions are given for the improvement of Eagle medium for cell growth. Supported by Research Grants CA 03720 and CA 11802 from the National Institutes of Health. Predoctoral, fellow supported, by Grant F01-GM-42156-02 from the National Institutes of Health.     

The effect of sugar,amino acid,metal ion,and NaCl on model Maillard reaction under pH control

Summary. The color intensities was determined of Maillard reaction products (MRPs) prepared by heating each of five sugars (maltose, fructose, glucose, arabinose, and xylose) with each of 12 amino acids (aspartic acid, glutamic acid, alanine, leucine, isoleucine, valine, proline, serine, cysteine, phenylalanine, arginine, and lysine). The remaining percentages of glucose and rate of change of color intensity due to the addition of a metal ion and NaCl were monitored for nine MRPs that had been formed between glucose and each of nine amino acids (aspartic acid, glutamic acid, alanine, valine, serine, cysteine, phenylalanine, arginine, and lysine). Model MRPs were prepared in a block heater at 100°C for 1–12h with the pH value controlled at 6.5. The resulting color intensity of each MRPs formed from the basic amino acids was greater due to the higher reactivity than those from the acidic amino acids. The remaining percentage of glucose in each MRPs from the basic amino acids was lower than those from the acidic amino acids. The MRPs from the nonpolar amino acids showed an intermediate color intensity and remaining percentages of glucose between those formed from the basic and acidic amino acids. Browning tended to be accelerated in the presence of metal ions, especially Fe²⁺ and Cu²⁺, although it was affected by the property of the amino acid and heating time as well as by the type of metal ion. On the other hand, browning was greatly inhibited by a high concentration of NaCl.     

Characterization and amino-terminal sequence of apolipoprotein AI from plasma high density lipoproteins in the preruminant calf, Bos spp

The major apolipoprotein of calf plasma high-density lipoproteins, apo-AI, has been isolated and characterized. Apolipoprotein AI (apo-AI) was separated from the protein moiety of high-density lipoproteins (d 1.090-1.180 g/ml) by preparative electrophoresis in SDS-polyacrylamide gels followed by electrophoretic elution. Purified calf apo-AI had an Mr of approx. 27,000-28,000 in SDS-polyacrylamide gels, resembling human apo-AI. The amino acid composition of calf apo-AI displayed an overall similarity to that of its human and other mammalian counterparts (baboon, dog, badger, rabbit, rat and mouse), but differed in having higher proportions of glutamic acid, alanine and isoleucine. Amino-terminal amino acid sequence analysis up to the 47th residue showed close homology between calf apo-AI and those of the mammals with which it was compared. However, residues 2, 7, 20 and 22 in calf AI (i.e. aspartic acid, serine, glutamic acid and isoleucine, respectively) were substituted by glutamic acid, proline or glutamine, aspartic acid, and valine or leucine respectively, in the other mammals.     

Speculations on the evolution of the genetic code II

An evolutionary scheme is postulated in which a primitive code, involving only guanine and cytosine, would code for glycine (GG), alanine (GC), arginine (CG) and proline (CC). From each of these amino acids and their codons, there evolves a family of related amino acids as the code expands. The four families are: (1)alanine valine, leucine, isoleucine, phenylalanine, tyrosine, methionine and tryptophane; (2)proline, threonine and serine; (3)arginine, lysine, and histidine; (4)glycine, serine, cysteine, glutamic acid, glutamine, aspartic acid and asparagine. Except for the glycine relation to glutamic acid and aspartic acid, all amino acids are related by chemical similarities in their side chains. Glycine not having a side chain would permit a more complex set of substitutions.     

Amino-acid profiles in red algae

Free protein amino acids have been quantitatively determined in 30 red algae. In most of the species, aspartic acid (asparagine), glutamic acid (glutamine), alanine, glycine and serine dominate, while massive accumulation of proline (up to 80·5%) was observed in six species, all belonging to the family Rhodomelaceae.     

Modulation of blackspot seabream (Pagellus bogaraveo) intermediary metabolic pathways by dispensable amino acids

The objective of the present work is to investigate the main metabolic pathways by which dispensable amino acids (DAA) are diverted towards lipid formation in blackspot seabream. For that purpose, a control diet was formulated to contain 45% of crude protein (7.2 g N/100 g dry matter) mainly supplied by fish meal (45P). In two other diets, 22.2% of the dietary nitrogen (1.6 g N/100 g dry matter) was replaced by an equivalent amount of nitrogen provided by two different mixtures of DAA: alanine and serine (diet AS) or aspartic and glutamic acid (diet AG). A fourth diet (diet 35P) only containing 35% of crude protein (5.6 g N/100 g dry matter) was included in order to analyze the possible additive effects of DAA. Compared to fish fed diet 35P, blackspot seabream appear to make a more efficient use of the nitrogen provided by alanine and serine than that provided by aspartic and glutamic acids in terms of growth. Contrary to fish fed AG, fish fed AS attained similar specific FAS activities as 45P fed fish, suggesting a further role of alanine and serine on this lipogenic pathway. Dietary nitrogen reduction (45P vs. 35P) or its replacement by a mixture of aspartic and glutamic acids (diet AG) were shown to up-regulate phosphoenolpyruvate carboxykinase (PEPCK) but without, however, any effect on plasma glucose levels. Dietary nitrogen level and nature seems to exert a complex regulation on energetic pathways through the gluconeogenesis/tricarboxylic acids cycle interaction.