Discussion: Amino-acid activation by individual enzymes

1958 ◽  
Vol 149 (936) ◽  
pp. 401-402
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Distribution Pattern ◽  
Mammary Tissue ◽  
Low Molecular Weight ◽  
Major Protein ◽  
Acid Activation ◽  
Amino Acid Activation ◽  
Interesting Paper

I should like to comment on one aspect of Dr Gutfreund’s interesting paper. As he mentioned, we have found evidence that amino acids, after becoming enzymically activated by ATP through the formation of an enzyme-bound amino acyladenylate compound, are transferred to a low molecular weight RNA which, by accident or design, resides in the same crude activating enzyme fraction. It is gratifying that Dr Gutfreund has found a distribution pattern of amino acids on this RNA which roughly agrees with the pattern in the major protein products of mammary tissue. He points out, however, that there is no such correlation when one looks at the pattern of amino-acid activation. Indeed, because of this anomaly, some workers have devised theories of activation involving transacylation steps to account for activation of those amino acids for which an enzyme has not been found. Dr Gutfreund implies that there is much confusion and mystery here, and even suggests that the specificity of activation might be accounted for by soluble RNA , rather than by individual enzymes.

Trans-tegumental absorption of L-alanine and L-leucine by a monogenean, Diclidophora merlangi

Parasitology ◽  
1978 ◽  
Vol 76 (1) ◽  
pp. 29-37 ◽  
Author(s):  
D. W. Halton
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Sea Water ◽  
Low Molecular Weight ◽  
Acid Uptake ◽  
Neutral Amino Acids ◽  
Freeze Dried ◽  
Significant Difference

SummaryAn in vitro investigation has been made of the relative roles of the gut and tegument in the absorption of the neutral amino acids L-alanine and L-leucine by a marine fish-gill parasite, Diclidophora merlangi. The use of ligatures to preclude oral ingestion of trace-labelled medium has proved inadequate, invariably damaging the tegument, as revealed by stereoscan electron microscopy, and resulting in artifactual levels of absorption. Three alternative procedures have given consistently reliable data on the route of entry of low molecular weight substrates. (1) Ultrastructural examination of worms previously incubated in electron-dense cationic tracers has shown that, in vitro, there is no oral intake of sea water. (2) The suspending of worms in trace-labelled medium with the mouth out of the medium and comparing amino acid uptake with that of worms totally immersed in medium has revealed no statistically significant difference in the absorption levels. (3) Application of section (freeze-dried) auto-radiography to detect diffusible isotope has demonstrated directly transtegumental absorption of a neutral amino acid. It is concluded from these experiments that Diclidophora has a tegumental transport system for absorbing certain neutral amino acids, and whilst, clearly, the worm is sanguinivorous and digests blood in a well-developed gut, it may also be capable of supplementing this diet with low molecular weight organic nutrient absorbed directly from sea water via the tegument.

scholarly journals The structure of a glycopeptide isolated from the yeast cell wall

1968 ◽  
Vol 109 (3) ◽  
pp. 419-432 ◽  
Author(s):  
R. Sentandreu ◽  
D. H. Northcote
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Cell Wall ◽  
Amino Acid ◽  
Yeast Cell ◽  
Aspartic Acid ◽  
Yeast Cell Wall ◽  
Low Molecular Weight ◽  
Elimination Reaction ◽  
Sephadex Column

1. Glycopeptides containing mannose were extracted from isolated yeast cell walls by ethylenediamine and purified by treatment with Pronase and fractionation on a Sephadex column. 2. A glycopeptide that appeared homogeneous on electrophoresis and ultracentrifugation had a molecular weight of 76000, and contained a high-molecular-weight mannan and approx. 4% of amino acids. 3. The amino acid composition of the peptide was determined. It was rich in serine and threonine and also contained glucosamine. No cystine and methionine were detected. 4. The glycopeptide underwent a β-elimination reaction when treated with dilute alkali at low temperatures. The reaction resulted in the release of mannose, mannose disaccharides and possibly other low-molecular-weight mannose oligosaccharides. During the β-elimination reaction the dehydro derivatives of serine and threonine were formed. One of the linkages between carbohydrate and amino acids in the glycopeptide is an O-mannosyl bond from mannose and mannose oligosaccharides to serine and threonine. 5. After the β-elimination reaction the bulk of the mannose in the form of the large mannan component was still covalently linked to the peptide. This polysaccharide was therefore attached to the amino acids by a linkage different from the O-mannosyl bonds to serine and threonine that attach the low-molecular-weight sugars. 6. Mannan was prepared from the glycopeptide and from the yeast cell wall by treatment of the fractions with hot solutions of alkali. The mannan contained aspartic acid and glucosamine and some other amino acids. The aspartic acid and glucosamine were present in equimolar amounts; the aspartic acid was the only amino acid present in an amount equivalent to that of glucosamine. Thus there is the possibility of a linkage between the mannan and the peptide via glucosamine and aspartic acid. 7. Mannose 6-phosphate was shown to be part of the mannan structure. Information about the structure of the mannan and the linkage of the glucosamine was obtained by periodate oxidation studies. 8. The glucosamine present in the glycopeptide could not be released by treatment with an enzyme preparation obtained from the gut of Helix pomatia. This enzyme released glucosamine from the intact cell wall. Thus there are probably at least two polymers containing glucosamine in the cell wall. 9. The biosynthesis of the mannan polymer in the yeast cell wall is discussed with regard to the two types of carbohydrate–amino acid linkages found in the glycoprotein.

scholarly journals Class III PI-3-kinase activates phospholipase D in an amino acid–sensing mTORC1 pathway

2011 ◽  
Vol 195 (3) ◽  
pp. 435-447 ◽  
Author(s):  
Mee-Sup Yoon ◽  
Guangwei Du ◽  
Jonathan M. Backer ◽  
Michael A. Frohman ◽  
Jie Chen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Phospholipase D ◽  
Acid Activation ◽  
Class Iii ◽  
Amino Acid Activation ◽  
Px Domain ◽  
Amino Acid Sensing ◽  
Mtorc1 Activation ◽  
Phosphatidylinositol 3

The rapamycin-sensitive mammalian target of rapamycin (mTOR) complex, mTORC1, regulates cell growth in response to mitogenic signals and amino acid availability. Phospholipase D (PLD) and its product, phosphatidic acid, have been established as mediators of mitogenic activation of mTORC1. In this study, we identify a novel role for PLD1 in an amino acid–sensing pathway. We find that amino acids activate PLD1 and that PLD1 is indispensable for amino acid activation of mTORC1. Activation of PLD1 by amino acids requires the class III phosphatidylinositol 3-kinase hVps34, which stimulates PLD1 activity through a functional interaction between phosphatidylinositol 3-phosphate and the Phox homology (PX) domain of PLD1. Furthermore, amino acids stimulate PLD1 translocation to the lysosomal region where mTORC1 activation occurs in an hVps34-dependent manner, and this translocation is necessary for mTORC1 activation. The PX domain is required for PLD1 translocation, mTORC1 activation, and cell size regulation. Finally, we show that the hVps34-PLD1 pathway acts independently of, and in parallel to, the Rag pathway in regulating amino acid activation of mTORC1.

scholarly journals Studien über Wespengift, I Niedermolekulare Bestandteile des Giftblasenextraktes von Paravespula vulgaris / Studies on Wasp Venom, I Low Molecular Weight Constituents of Venom Sac Extracts from Paravespula vulgaris

1981 ◽  
Vol 36 (6) ◽  
pp. 757-762 ◽  
Author(s):  
Hartmut Klein ◽  
Wittko Francke ◽  
Wilfried A. König
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Fatty Acids ◽  
Molecular Weight ◽  
Gas Chromatography ◽  
Acetic Acid ◽  
Quantitative Analysis ◽  
Amino Acid ◽  
Low Molecular Weight ◽  
Wasp Venom

Abstract Low molecular weight constituents of 3400 venom sacs of Paravespula vulgaris were extracted with water, diluted acetic acid, and methanol. After conversion to volatile derivatives carbohydrates, amino acids, fatty acids, other constituents of phospho lipids, and biogenic amines were identified by gas chromatography and mass spectrometry. Quantitative analysis was achieved for amino acids by amino acid analysis and for glucose by an enzymatic assay. Results are discussed with regard to biosynthesis of wasp toxins and phylogenetic aspects of hymenopteran venoms.

scholarly journals Obtaining and estimating the potential of protein nutraceuticals from highly mineralized collagen-containing beef raw materials

2021 ◽  
Vol 6 (1) ◽  
pp. 10-22
Author(s):  
N. Yu. Mezenova ◽  
S. V. Agafonova ◽  
O. Ya. Mezenova ◽  
L. S. Baidalinova ◽  
T. Grimm
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Raw Materials ◽  
Water Soluble ◽  
Biologically Active ◽  
Low Molecular Weight ◽  
Enzyme Preparations ◽  
Freeze Dried ◽  
Mineralized Collagen

Highly mineralized collagen-containing beef raw materials (tibia, fibula and costal bones) are a source of valuable protein nutraceuticals. They include high molecular weight proteins, oligopeptides and amino acids, which anabolic and physiological potential is used insufficiently. Protein nutraceuticals were obtained by high-temperature hydrolysis of beef raw materials in combination with enzymolysis by proteolytic enzyme preparations Alcalase 2,5 L, Protamex, Protosubtilin G3x. The water-soluble fraction of hydrolysates was studied after its separation and freeze-drying on the content of nitrogenous compounds, fats, minerals, formol-titrated nitrogen, fractional molecular composition. The mathematical dependencies of accumulation of low molecular weight products of protein hydrolysis on enzymolysis duration and doses of different enzyme preparations were obtained. The rational technological scheme of complex processing of beef raw materials with production of protein, fat and mineral-protein additives was proposed. The protein weight fraction in the freeze-dried protein hydrolysates was 69.5–89.6%. All studied protein additives contained peptides with a molecular weight of not more than 100 kDa. The content of low-molecular weight oligopeptides with a molecular weight of less than 10 kDa in the protein additives obtained by enzymatic thermal hydrolysis was more than 90%. The amino acid composition of protein additives produced by different hydrolytic methods was analyzed. Sensory and functional-technological properties of freeze-dried protein compositions were studied. The amino acid potential, high assimilability and physiological activity of protein nutraceuticals from collagen-containing beef raw materials were established. It is recommended to use them in the composition of specialized biologically active additives (BAAs) to food of the osteotropic direction in recipes of specialized and personalized products as a source of amino acids and active peptides.

Antioxidant and Hypolipidemic Potential of Peptides from Broccoli Stems and Leaves

2018 ◽  
Vol 18 (1) ◽  
pp. 16-20
Author(s):  
Chen Hua ◽  
Xia Li-Shan ◽  
Zhang Xu-Dong
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Antioxidant Activity ◽  
Amino Acid ◽  
Nutritive Value ◽  
Reduced Glutathione ◽  
Low Molecular Weight ◽  
Weight Analysis ◽  
Stems And Leaves ◽  
Scavenging Rates

To isolate bioactive broccoli peptides, crude proteins were flocculated from heated juice of broccoli stems and leaves and then hydrolyzed by proteases. Different proteases yielded different peptides with a significant effect on the bio-activities of broccoli peptides. Antioxidant activity of the broccoli peptides was investigated by measuring their DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals scavenging action in comparison to native antioxidants, reduced glutathione (GSH) and soybean peptides. Broccoli peptides (obtained by Neutrase® hydrolysis) at 5.0 mg/mL exhibited 72.8% of radicals scavenging rates, resembling GSH at 1.0 mg/mL (72.1%), and was 2.8 times than that of soybean peptides at 5.0 mg/mL (25.7%). Subsequently, the hypolipidemic activities were measured by oral gastric gavage of broccoli peptides in hyperlipemic golden hamster. Treatment with broccoli peptides (obtained by papain hydrolysis) significantly decreased the serum TC and LDL-C levels (P < 0.01) in experimental rats. The constitution of amino acid and the distribution of molecular weight analysis showed broccoli peptides contained sixteen amino acids and a great percentage of low molecular weight peptides (<1 kDa, 77.67%). By analyzing the amino acid compositions and bio-activities, our results indicate the high nutritive value and possible applications of broccoli peptides for human health.

Synthesis and evaluation of chiral β-amino acid-based low-molecular-weight organogelators possessing a methyl/trifluoromethyl side chain

2019 ◽  
Vol 43 (7) ◽  
pp. 2882-2887 ◽  
Author(s):  
Koichi Kodama ◽  
Ryuta Kawamata ◽  
Takuji Hirose
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Supramolecular Structures ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Side Chains ◽  
Low Molecular Weight Organogelators

Impacts of side-chains and chirality of organogelators derived from β-amino acids are described with their supramolecular structures.

NON-RIBOSOMAL POLYPEPTIDE SYNTHESIS

1973 ◽  
Vol 74 (Suppl) ◽  
pp. S294-S300 ◽  
Author(s):  
Fritz Lipmann
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Activation ◽  
Bacillus Brevis ◽  
Amino Acid Activation ◽  
Molecular Weights ◽  
Polypeptide Synthesis ◽  
Secondary Transfer ◽  
Sequential Addition ◽  
Made In

ABSTRACT The biosynthesis of the cyclic decapeptide antibiotic, tyrocidine, was analyzed in particle-free supernatant fractions of RNase-treated homogenates of Bacillus brevis ATCC 8185. From the extracts, three complementary fractions with molecular weights of (1) 100 000, (2) 230 000, and (3) 440 000 were obtained. (1) activates and racemizes the initiating phenylalanine, (2) activates the three following amino acids, and (3) activates the last six amino acids by primary reaction with ATP to AMP-amino acid and secondary transfer to an enzyme-bound -SH. The enzymes alone fix amino acids but do not polymerize. The mixture, on sequential addition of amino acids + ATP, polymerizes first to enzyme-bound polypeptides, which after addition of all ten amino acids, cyclize. The enzymes (2) and (3) each contain one mole of 4'-phosphopantetheine which appears to act in transpeptidation. By mild autolysis and dodecyl sulphate gel electrophoresis, the polyenzymes may be split to subunits of 70 000 molecular weight, retaining only amino acid activation. In recent attempts to analyze the biosynthesis of the thyrotropic release hormone, a tripeptide made in the hypothalamus, we have met with great difficulties due to the presence of potent peptidases in brain preparations.

CHARACTERIZATION OF THE PIGMENT OF MICROCOCCUS VIOLAGABRIELLAE

1964 ◽  
Vol 10 (5) ◽  
pp. 659-675 ◽  
Author(s):  
J. N. Campbell ◽  
J. L. Nichols ◽  
Sheila A. Berry
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Cross Reactivity ◽  
Low Molecular Weight ◽  
Terminal Amino Acid ◽  
Iron Chelate ◽  
Peptide Moiety ◽  
Terminal Amino

Production of the red insoluble pigment by Micrococcus violagabriellae was studied. Pigmentation was found to require oxygen and high levels of iron and to be stimulated by tryptophan alone among the amino acids. The pigment was isolated, purified, and analyzed chemically and spectrophotometrically. It was found to be similar to pulcherrimin from Candida pulcherrima. Immunological cross reactivity and analysis of derivatives confirmed the similarity between the bacterial and yeast pigments. From these data it is postulated that the pigment is an iron chelate of pulcherriminic acid with an associated low molecular weight peptide moiety with glycine as the sole N-terminal amino acid. The pigment appears to differ from that of C. pulcherrima solely with respect to this peptide and in the mode of aggregation of the molecule.

Complete Covalent Structure of Human Platelet Factor 4

1979 ◽  
Vol 42 (05) ◽  
pp. 1652-1660 ◽  
Author(s):  
Francis J Morgan ◽  
Geoffrey S Begg ◽  
Colin N Chesterman
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Human Platelet ◽  
Platelet Factor 4 ◽  
Platelet Factor ◽  
Disulphide Bonds ◽  
Covalent Structure

SummaryThe amino acid sequence of the subunit of human platelet factor 4 has been determined. Human platelet factor 4 consists of identical subunits containing 70 amino acids, each with a molecular weight of 7,756. The molecule contains no methionine, phenylalanine or tryptophan. The proposed amino acid sequence of PF4 is: Glu-Ala-Glu-Glu-Asp-Gly-Asp-Leu-Gln-Cys-Leu-Cys-Val-Lys-Thr-Thr-Ser- Gln-Val-Arg-Pro-Arg-His-Ile-Thr-Ser-Leu-Glu-Val-Ile-Lys-Ala-Gly-Pro-His-Cys-Pro-Thr-Ala-Gin- Leu-Ile-Ala-Thr-Leu-Lys-Asn-Gly-Arg-Lys-Ile-Cys-Leu-Asp-Leu-Gln-Ala-Pro-Leu-Tyr-Lys-Lys- Ile-Ile-Lys-Lys-Leu-Leu-Glu-Ser. From consideration of the homology with p-thromboglobulin, disulphide bonds between residues 10 and 36 and between residues 12 and 52 can be inferred.

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