Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ASPARTIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,801 records · Page 100Linked to original sources
PubMedDate not supplied

Excitatory amino acids in cerebrospinal fluid in neonatal asphyxia.

Of the excitatory amino acids, glutamic and aspartic acid were studied in the cerebrospinal fluid of six infants 4-32 hours after a documented episode of severe neonatal asphyxia. Aspartic acid concentration was definitely increased in the cerebrospinal fluid of these patients, whereas glutamic acid concentration varied considerably. Aspartic acid was always increased, even hours after the period of asphyxia, but values were greater in samples taken less than 12 hours after the asphyxial event. The patients with the highest cerebrospinal fluid aspartic acid concentrations had more severe outcomes.

Aspartic Acid↗
PubMed1974

Navy (Haricot)-bean (Phaseolus vulgaris) lectin. Isolation and characterization of tow components from a toxic agglutinating extract.

Two protein components were isolated in a highly purified state from a toxic fraction from the navy (haricot) bean (Phaseolus vulgaris). One, a lectin, strongly agglutinated horse erythrocytes and leucocytes, agglutination being readily observable with both types of cell at a lectin concentration of 4mug/ml. The other component (component 1), although possessing some similarity in composition, was thought to be non-agglutinating or, at most, only very weakly so. Component 1 had a mol.wt. of about 143000 and a subunit mol.wt. of about 37000, suggesting a tetrameric structure probably with identical subunits. Alanine was the only N-terminal amino acid identified and the molecule was notable in being devoid of tryptophan and cysteine, low in methionine and high in leucine, glutamic acid and aspartic acid. The lectin was somewhat smaller (mol.wt. about 114000) and apparently also composed of four identical subunits of mol.wt. about 30000. Dansylation showed that arginine occupied the N-terminus of the polypeptide chain. Aspartic acid, serine, threonine and leucine were the predominant amino acids of the lectin, and the sulphur-containing amino acids were entirely absent. Both constituents were glycoproteins and the compositions of the carbohydrate portions (4.9% for component 1 and 8.1% for the lectin) were generally similar, consisting of mannose and glucosamine with smaller amounts of glucose and traces of xylose and arabinose.

Alanine↗
PubMed2005

Differentiation of aspartic and isoaspartic acids using electron transfer dissociation.

Electron-transfer dissociation allows differentiation of isoaspartic acid and aspartic acid residues using the same c + 57 and z - 57 peaks that were previously observed with electron capture dissociation. These peaks clearly define both the presence and the position of isoaspartic acid residues and they are relatively abundant. The lower resolution of the ion trap instrument makes detection of the aspartic acid residue's diagnostic peak difficult because of interference with side-chain fragment ions from arginine residues, but the aspartic acid residues are still clearly observed in the backbone cleavages and can be inferred from the absence of the isoaspartic acid diagnostic ions.

Aspartic Acid↗
PubMed1962

Culture and metabolism of Mycoplasma gallisepticum.

Gill, James W. (University of New Hampshire, Durham). Culture and metabolism of Mycoplasma gallisepticum. J. Bacteriol. 83:213-218. 1962.-Mycoplasma gallisepticum A5969, a strong-growing pleuropneumonia-like organism pathogenic for poultry, was found to be intolerant of extremes of temperature and potassium ion concentration. It ferments glucose to the benefit of cell yield, but glycolysis appears not to be essential to growth. Anaerobic growth can be maintained if pyruvate is added as a hydrogen recipient.A transamination system between glutamic acid and aspartic acid, more rapid toward the formation of aspartic acid, was found in a frozen-cell preparation. Two small peptides were observed to be produced by the organism and liberated into the medium under normal growth conditions. The composition of the peptides shows a relationship to the cell wall of certain bacteria.

Glucose↗
PubMed1993

Characterization of a novel dentin matrix acidic phosphoprotein. Implications for induction of biomineralization.

Acidic phosphorylated proteins have been shown to be prominent constituents of the extracellular matrix of bone and dentin. The acidic phosphoproteins of bone contain more glutamic acid than aspartic acid and a lower serine content than either. On the other hand, the major dentin acidic phosphoproteins, phosphophoryns, have been defined as aspartic acid- and serine-rich proteins, with a lesser content of glutamic acid. Both sets of phosphoproteins have been implicated as key participants in regulating mineralization, but it has been difficult to unify their mechanisms of action. We have now identified, by cDNA cloning, a new serine-rich acidic protein of the dentin matrix, AG1, with a composition intermediate between the bone acidic proteins and dentin phosphophoryns. AG1 has numerous acidic consensus sites for phosphorylation by both casein kinases I and II. Immunochemical and organ culture biosynthetic studies show that AG1 is present in phosphorylated form at low levels in the dentin matrix. If fully phosphorylated, AG1 would bear a net charge of -175/molecule of 473 residues. AG1 contains single RGD integrin binding and N-glycosylation sequences. The overall picture that emerges is that of a matrix-associated acidic phosphoprotein, with a potentially high calcium ion binding capacity, present at levels compatible with a regulatory role in dentin mineralization.

Amino Acid Sequence↗
PubMed1989

Proteaselike sequence in hepatitis B virus core antigen is not required for e antigen generation and may not be part of an aspartic acid-type protease.

The hepatitis B virus (HBV) C gene directs the synthesis of two major gene products: HBV core antigen (HBcAg[p21c]), which forms the nucleocapsid, and HBV e antigen (HBeAg [p17e]), a secreted antigen that is produced by several processing events during its maturation. These proteins contain an amino acid sequence similar to the active-site residues of aspartic acid and retroviral proteases. On the basis of this sequence similarity, which is highly conserved among mammalian hepadnaviruses, a model has been put forward according to which processing to HBeAg is due to self-cleavage of p21c involving the proteaselike sequence. Using site-directed mutagenesis in conjunction with transient expression of HBV proteins in the human hepatoma cell line HepG2, we tested this hypothesis. Our results with HBV mutants in which one or two of the conserved amino acids have been replaced by others suggest strongly that processing to HBeAg does not depend on the presence of an intact proteaselike sequence in the core protein. Attempts to detect an influence of this sequence on the processing of HBV P gene products into enzymatically active viral polymerase also gave no conclusive evidence for the existence of an HBV protease. Mutations replacing the putatively essential aspartic acid showed little effect on polymerase activity. Additional substitution of the likewise conserved threonine residue by alanine, in contrast, almost abolished the activity of the polymerase. We conclude that an HBV protease, if it exists, is functionally different from aspartic acid and retroviral proteases.

Amino Acid Sequence↗
PubMed2004

The pattern and kinetics of substrate metabolism of Campylobacter jejuni and Campylobacter coli.

AIMS: The main aim was to investigate the patterns and kinetics of substrate oxidation by Campylobacter jejuni and C. coli. METHODS AND RESULTS: Substrate oxidation profiles by 100 strains were determined using oxygen electrode system. All the isolates tested oxidized formate, l-lactate, cysteine, glutamine and serine with high oxidation rates and high affinity but varied in their ability to oxidize citric acid cycle intermediates, aspartic acid and serine. CONCLUSIONS: Based on the oxidation ability of alpha-ketoglutarate, succinate, fumarate and aspartic acid, Campylobacter strains tested were divided into three distinct metabolic categories. The first group was able to metabolize alpha-ketoglutarate, succinate, fumarate and aspartic acid; the second group was unable to oxidize alpha-ketoglutarate; and the third group was unable to oxidize, succinate, fumarate, and aspartic acid. Furthermore, serine oxidation rate enabled the differentiation of C. jejuni and C. coli. SIGNIFICANCE AND IMPACT OF THE STUDY: Overall, the results highlights the extensive metabolic diversity between and within Campylobacter species. In addition, the kinetic data of oxidized substrates obtained may improve the isolation procedures of the organism.

Bacterial Typing Techniques↗
PubMed2004

Probing crystallization of calcium oxalate monohydrate and the role of macromolecule additives with in situ atomic force microscopy.

Kidney stones are crystal aggregates, most commonly containing calcium oxalate monohydrate (COM) microcrystals as the primary constituent. Macromolecules, specifically proteins rich with anionic side chains, are thought to play an important role in the regulation of COM growth, aggregation, and attachment to cells, all key processes in kidney stone formation. The microscopic events associated with crystal growth on the [010], [121], and [100] faces have been examined with in situ atomic force microscopy (AFM). Lattice images of each face reveal two-dimensional unit cells consistent with the COM crystal structure. Each face exhibits hillocks with step sites that can be assigned to specific crystal planes, enabling direct determination of growth rates along specific crystallographic directions. The rates of growth are found to depend on the degree of supersaturation of calcium oxalate in the growth medium, and the growth rates are very sensitive to the manner in which the growth solutions are prepared and introduced to the AFM cell. The addition of macromolecules with anionic side chains, specifically poly(acrylic acid), poly(aspartic acid), and poly(glutamic acid), results in inhibition of growth on the hillock step planes. The magnitude of this effect depends on the macromolecule structure, macromolecule concentration, and the identity of the step site. Poly(acrylic acid) was the most effective inhibitor of growth. Whereas poly(aspartic acid) inhibited growth on the (021) step planes of the (100) hillocks more than poly(glutamic acid), the opposite was found for the same step planes on the (010) hillocks. This suggests that growth inhibition is due to macromolecule binding to both planes of the step site or pinning of the steps due to binding to the (100) and (010) faces alone. The different profiles observed for these three macromolecules argue that local binding of anionic side chains to crystal surface sites governs growth inhibition rather than any secondary polymer structure. Growth inhibition by cationic macromolecules is negligible, further supporting an important role for proteins rich in anionic side chains in the regulation of kidney stone formation.

Journal Article↗
PubMed1995

Structure-function studies of waglerin I, a lethal peptide from the venom of Wagler's pit viper, Trimeresurus wagleri.

Waglerins are 22-24 residue lethal peptides, found in the venom of Trimeresurus (Tropidolaemus) wagleri. The effects upon lethality and immunoreactivity resulting from structural modifications of these peptides were studied. A synthetic analogue with alanine residues in place of the two half-cystines of native peptide was nontoxic, suggesting that the single intramolecular disulfide bond in waglerins is critical for bioactivity. Substituting glutamic acid for aspartic acid at residue 5 slightly diminished lethality. Analogues containing asparagine instead of aspartic acid at residue 5 and/or a carboxamide- instead of a carboxy-terminus were lethal, demonstrating that neither a negative charge on residue 5 nor on the carboxy-terminus was required for bioactivity. A proteolytic fragment of waglerin I containing residues 6-22 was isolated and proved nontoxic. Therefore, one or more of the first five residues were necessary for bioactivity. Antiserum against waglerin I bound strongly to waglerins I, II, and SL-I, and to various analogues, proteolytic fragments, and chemically modified waglerin I. These findings suggest that the antibodies might be directed mainly against short, linear epitopes, implying an extended conformation for waglerin I.

Amino Acid Sequence↗
PubMed1979

Production of exotoxin A by Pseudomonas aeruginosa in a chemically defined medium.

A defined medium was developed in which easily measured quantities of exotoxin A (PE) were produced by Pseudomonas aeruginosa PA-103. The medium contained three L-amino acids (arginine, aspartic acid, and alanine), basal and trace salts including 14 mM K2HPO4, 14 mM glucose, and 140 mM glycerol. The concentrations of amino acids which yielded most satisfactory results were 6 mM alanine, 13 mM aspartic acid, and 16 mM arginine. The identity of PE in the culture supernatant fluid was demonstrated by adenosine diphosphate-ribosyl transferase activity and by immunodiffusion with sheep antitoxin elicited with purified PE and with PE produced in Trypticase soy broth dialysate and pure PE as controls. PE production was also demonstrated by mouse lethality and passive hemagglutination. As compared to Trypticase soy broth dialysate, P. aeruginosa produced 25 to 50% PE in the defined medium. Different strains of P. aeruginosa produced PE in the defined medium in proportions relative to those in Trypticase soy broth dialysate.

Amino Acids↗
PubMed1989

[Effect of acute poisoning of rats with carbaryl on transamination reactions with involving pyruvate. III. Supplementary studies of plasma aminotransferases].

Male Wistar rats were poisoned orally with one carbaryl dose 474 mg/kg (1/2 DL50). After 2, 4, 24 and 72 hours from the administration of the insecticide the activity of plasma aminotransferases catalysing the reactions between pyruvate and the following amino acids: asparagine, aspartic acid, glutamic acid, isoleucine, lysine and valine was determined. Under physiological conditions these amino acids are not participating in the transamination reactions. The activity of aminotransferases was expressed as the amount of alanine developing during incubation of 1 ml of plasma for 1 hour. Alanine was determined spectrophotometrically after chromatographic separation on paper. The results of the investigations demonstrated that acute poisoning with carbaryl caused the appearance of activity of all studied plasma aminotransferases, except for the enzyme catalysing the reaction between pyruvate and lysine. The activity of the studied aminotransferases appeared as follows: glutamic acid--pyruvate--4 hr; isoleucine--pyruvate--24 and 72 hr; asparagine--pyruvate, aspartic acid--pyruvate and valine--pyruvate--72 hr after intoxication.

Amino Acids↗
PubMed1991

Structural requirements of position A alpha-157 in fibrinogen for the fibrin-induced rate enhancement of the activation of plasminogen by tissue-type plasminogen activator.

The sequence fibrinogen-A alpha-(148-160) can mimic part of the fibrin-induced rate enhancement of the activation of plasminogen by tissue-type plasminogen activator. Previously we have reported that the lysine residue at position A alpha-157 is crucial. During our further investigations on A alpha-157 we found that lysine at position A alpha-157 may be replaced by glutamic acid. This unexpected finding prompted us to re-investigate the requirements of this position. We prepared analogues of A alpha-(148-160) in which the lysine residue at position A alpha-157 was replaced by lysine derivatives (acetyl-lysine, benzyloxycarbonyl-lysine and methanesulphonylethyloxycarbonyl-lysine), acidic residues (aspartic acid and glutamic acid), basic residues (arginine and ornithine), polar residues (glutamine and methanesulphonylethyloxycarbonylornithine), apolar residues (alanine, valine, norleucine and glutamic acid 4-nitrobenzyl ester) and glycine. These analogues were tested for their stimulatory activity. When aspartic acid, glutamic acid 4-nitrobenzyl ester or norleucine is present at position A alpha-157 in A alpha-(148-160) virtually all stimulatory capacity is lost. With valine at position A alpha-157 the stimulatory activity is marginal. None of the other replacements at position A alpha-157 caused loss of rate-enhancing properties. From these results we conclude that for the rate-enhancing effect of A alpha-(148-160) the side chain of the amino acid residue at position A alpha-157 must fulfill certain requirements: there must be one (as in alanine) or no (as in glycine) carbon atom in the side chain, or at least two carbon atoms and a polar group (charged or uncharged) to which a rather bulky group (such as the benzyloxycarbonyl group) or a polar group (such as the methanesulphonylethyloxycarbonyl group) may be attached. The highest activity [even higher than native A alpha-(148-160)] was obtained with ornithine, methanesulphonylethyloxycarbonylornithine or methanesulphonylethyloxycarbonyl-lysine at position A alpha-157.

Amino Acid Sequence↗
PubMedDate not supplied

[Maternal and foetal aminoacidaemia and amino acids contents of amniotic fluid in normal, gestosic and diabetic pregnancy (author's transl)].

The AA. have examined 9 cases of normal pregnancy, 5 cases of E.P.H. gestosis and 5 cases of diabetes mellitus, for which cases caesarean section had been planed, determining the aminogram of the amniotic fluid, of the mother's venous plasma and of the umbilical venous plasma; the 3 samples were performed about contemporaneously. Both in the normal pregnancies and in those complicated by E.P.H. gestosis and by diabetes mellitus, the concentration of amino acids was higher in the umbilical venous plasma than in that of the mother and higher in the latter than in the amniotic fluid, with the exception of glycine, taurine, glutammic acid and aspartic acid in the normal pregnancies, of taurine in the gestosic pregnancies, of taurine, citrulline, glutammic and aspartic acid in the diabetic pregnancies.

Amino Acids↗
PubMed2002

Direct extract derivatization for determination of amino acids in human urine by gas chromatography and mass spectrometry.

The purpose of this study was to develop a simple and accurate analytical method to determine amino acids in urine samples. The developed method involves the employment of an extract derivatization technique together with gas chromatography-mass spectrometry (GC-MS). Urine samples (300 microl) and an internal standard (10 microl) were placed in a screw tube. Ethylchloroformate (50 microl), methanol-pyridine (500 microl, 4:1, v/v) and chloroform (1 ml) were added to the tube. The organic layer (1 microl) was injected to a GC-MS system. In this proposed method, the amino acids in urine were derivatized during an extraction, and the analytes were then injected to GC-MS without an evaporation of the organic solvent extracted. Sample preparation was only required for ca. 5 min. The 15 amino acids (alanine, aspartic acid, cysteine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, tyrosine, tryptophan, valine) quantitatively determined in this proposed method. However, threonine, serine, asparagine, glutamine, arginine were not derivatized using any tested derivatizing reagent. The calibration curves showed linearity in the range of 1.0-300 microg/ml for each amino acid in urine. The correlation coefficients of the calibration curves of the tested amino acids were from 0.966 to 0.998. The limit of detection in urine was 0.5 microg/ml except for aspartic acid. This proposed method demonstrated substantial accuracy for detection of normal levels. This proposed method was limited for the determination of 15 amino acids in urine. However, the sample preparation was simple and rapid, and this method is suitable for a routine analysis of amino acids in urine.

Amino Acids↗
PubMed1974

Lysine Biosynthesis in Barley (Hordeum vulgare L.).

Lysine biosynthesis in seedlings of barley (Hordeum vulgare L. var. Emir) was studied by direct injection of the following precursors into the endosperm of the seedlings: acetate-1-(14)C; acetate-2-(14)C; pyruvate-1-(14)C; pyruvate-2-(14)C; pyruvate-3-(14)C; alanine-1-(14)C; aspartic acid-1-(14)C; aspartic acid-2-(14)C; aspartic acid-3-(14)C; aspartic acid-4-(14)C; alpha-aminoadipic acid-1-(14)C; and alpha, epsilon-diaminopimelic acid-1-(7)-(14)C. The distribution of activity in the individual carbon atoms of lysine in the different biosynthetic experiments was determined by chemical degradation. The incorporation percentages and labeling patterns obtained are in agreement with the occurrence of the diaminopimelic acid pathway. The results do not fit the incorporation percentages and labeling patterns expected if the alpha-aminoadipic acid pathway was operating. However, the results show that barley seedlings are able to convert a small part of the alpha-aminoadipic acid administered directly to lysine.The labeling pattern of lysine was found to be symmetrical around carbon 4. This indicates that the biosynthetic pathway proceeds via a symmetrical intermediate like ll-alpha, epsilon-diaminopimelic acid, or includes compounds as 2, 3-dihydrodipicolinic acid or Delta(1)-piperideine-2, 6-dicarboxylic acid which probably isomerise with concomitant lack of asymmetry in the labeling. The percentages of incorporation show that both the mesoand ll-forms of alpha, epsilon-diaminopimelic acid are metabolically convertible to lysine in seedlings of barley.

Journal Article↗
PubMed1963

Gamma irradiation of polypeptides: transformation of amino acids.

The formation of aspartic acid from glutamic acid, of aspartic and glutamic acids from proline, of alpha-amino-n-butyric acid from methionine, of aspartic acid from histidine, of dihydroxyphenylalanine from tyrosine, of tyrosine and dihydroxyphenylalanine from phenylalanine, of alanine from cysteine, and of glycine from alanine was observed when aqueous solutions of these amino acids in the form of peptides or polyamino acids were irradiated. When poly-L-glutamic acid or poly-L-proline was irradiated in the presence of C(14)-labeled NaHCO(3), the radioactive carbon was fixed by the aspartic and the glutamic acid.

Alanine↗
PubMed1967

Tracer studies on the biosynthesis of amino acids from lactate by Peptostreptococcus elsdenii.

Peptostreptococcus elsdenii, a strict anaerobe from the rumen, was grown on a medium containing yeast extract and [1-(14)C]- or [2-(14)C]-lactate. Radioisotope from lactate was found in all cell fractions, but mainly in the protein. The label in the protein fraction was largely confined to a few amino acids: alanine, serine, aspartic acid, glutamic acid and diaminopimelic acid. The alanine, serine, aspartic acid and glutamic acid were separated, purified and degraded to establish the distribution of (14)C from lactate within the amino acid molecules. The labelling patterns in alanine and serine suggested their formation from lactate without cleavage of the carbon chain. The pattern in aspartic acid suggested formation by condensation of a C(3) unit derived directly from lactate with a C(1) unit, probably carbon dioxide. The distribution in glutamic acid was consistent with two possible pathways of formation: (a) by the reactions of the tricarboxylic acid cycle leading from oxaloacetate to 2-oxoglutarate, followed by transamination; (b) by a pathway involving the reaction sequence 2 acetyl-CoA-->crotonyl-CoA-->glutaconate-->glutamate.

Amino Acids↗

Refine your search to explore more results.