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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Kinetic studies have been performed on the "family" of aminoacyl synthetases from calf liver. All assays were based on the esterification of amino acids to tRNA. Optimized reaction conditions for each synthetase are reported. Most of the synthetases show hyperbolic kinetics with respect to both amino acid and tRNA concentration, however a few show sigmoidal kinetics with respect to one substrate. Arginine, methionine and proline synthetases show sigmoidal kinetics with respect to mixed tRNA solutions and have Hill coefficients of 1.30, 1.10 and 1.20 respectively. Alanine and isoleucine synthetases show sigmoidal kinetics with respect to amino acid concentration and have Hill coefficients of 1.21 and 1.40 respectively.
Mol Cell Biochem 1977 Aug 19
PMID:Aminoacyl-tRNA synthetases from calf liver: optimized assay conditions and kinetic properties. 2 May 69

The current status of the purification and characterization of human angiotensinogen is reviewed. One problem encountered in the past has been the copurification of a protein with similar porperties. This protein has tentatively been designated alanine-protein. An efficient separation of angiotensinogen and alanine-protein was obtained on a zinc chelate column. Alanine-protein has been purified and its amino acid and carbohydrate composition determined. The COOH-terminal amino acid and the NH2-terminal amino acid were determined to be serine and alanine, respectively. Alanine-protein exhibited multiple forms on isoelectric focusing.
Mol Cell Biochem 1979 Sep 28
PMID:Human plasma angiotensinogen: a review of purification procedures. 39 Mar 63

The effect of the exchangeable cation on the condensation of glycine and alanine was investigated using a series of homoinic bentonites. A cycling procedure of drying, warming and wetting was employed. Peptide bond formation was observed, and the effectiveness of metal ions to catalyze the condensation was Cu2+ greater than Ni2+ approximately Zn2+ greater than Na+. Glycine showed 6% of the monomer incorporated into oligomers with the largest detected being the pentamer. Alanine showed less peptide bond formation (a maximum of 2%) and only the dimer was observed.
J Mol Evol 1979 Nov
PMID:The role of metal ions in chemical evolution: polymerization of alanine and glycine in a cation-exchanged clay environment. 51 39

Alanine, starting from alanine-adenylate, has been polymerized in the presence of non-swelling Al-montmorillonite. The yield of polymerization is much lower than that obtained in the presence of swelling Na-montmorillonite. The possibility that the changing interlayer spacing in Na-montmorillonite might be responsible for its catalytic properties, is discussed.
J Mol Evol 1977 Sep 20
PMID:Polymerization of alanine in the presence of a non-swelling montmorillonite. 90 86

The filarial parasite Litomosoides carinii was able to survive for longer than 15 h in basic filarial medium (BFM) containing either glutamine or alanine as a sole substrate. The filariids were more motile in BFM containing glucose, but even higher motility was recorded in media containing both glucose and glutamine. Incubations under aerobic conditions showed that radiolabelled glutamine was metabolised primarily to CO2. In addition, small amounts of lactate and acetate were excreted in almost equimolar quantities. Incubations where both glutamine and glucose were present demonstrated that the glutamine carbon utilised by the parasite could be completely recovered in the above three end products. The glutamine nitrogen could be recovered in the additional excretory products, alanine and ammonia. The glutamine-dependent viability of L. carinii was affected by known inhibitors of the mitochondrial respiratory chain. Glucose utilisation, and the production of CO2 from this substrate, were greatly stimulated by the presence of glutamine in the external medium. Various carbon balance studies, in conjunction with enzymatic analyses, suggest that in L. carinii, glutamine provides an input of carbon into the tricarboxylic acid (TCA) cycle, probably at the level of alpha-ketoglutarate. This increased availability of Krebs cycle intermediates will stimulate the rate of pyruvate oxidation via acetyl-CoA and the TCA cycle, and thus increase the rate of carbon flux through glycolysis. The energetic advantage associated with the utilisation of the glucose/glutamine substrate couple may explain the worm's enhanced motor activity compared to incubations with glucose as the sole energy source. Alanine was found to be degraded by the filariid to equivalent amounts of lactate, acetate and CO2, indicating a relatively low energetic efficiency. There was no detectable uptake of glutamate. A variety of other amino acids tested were neither metabolised nor able to maintain worm viability in vitro.
Mol Biochem Parasitol 1990 Jun
PMID:The role of amino acids in the energy generating pathways of Litomosoides carinii. 211 54

The amino acid pool sizes of Trichomonas vaginalis are reported. Alanine, glutamic acid, proline and leucine account for 72% of the measured amino acids. Growth of T. vaginalis was unaffected by gostatin, an irreversible inhibitor of aspartate aminotransferase, when the enzyme activity within the cell had been completely inhibited and a specific elevation of the aspartate pool had occurred. In media lacking aspartate and glutamate, the amino acid substrates of the aspartate aminotransferase reaction, gostatin caused a larger increase in the aspartate pool. During incubation of cells with or without gostatin, aspartate and glutamate were produced in the medium, presumably by proteolysis of medium proteins. Hence any requirement for the aspartate aminotransferase reaction might have been bypassed. Glutamate-gamma-hydroxamate and aminooxyacetate inhibited growth of T. vaginalis but caused large changes in the pool-sizes of aspartate, glutamate, pyruvate plus oxaloacetate and 2-oxoglutarate, suggesting a more general interference with amino acid metabolism.
Mol Biochem Parasitol 1986 Oct
PMID:Modulation of amino acid and 2-oxo acid pools in Trichomonas vaginalis by aspartate aminotransferase inhibitors. 287 95

Chinese hamster ovary cells (CHO-K1) starved for 24 h for amino acids show a severalfold increase in velocity of proline transport through the A system (Vmax is five times that of unstarved cells). This increase is inhibited by cycloheximide, actinomycin D, N-methyl-alpha-amino isobutyric acid (MeAIB, a non-metabolizable specific A system amino acid analog), and by other amino acids that are generally transported by the A system. However, transport by the A system is not a prerequisite for this repression, and all compounds that have affinity for the A system do not necessarily act as "co-repressors." The addition of proline, MeAIB, or other amino acids, as described above, to derepressed cells results in a rapid decrease in A system activity. As shown with proline and MeAIB, this decrease in activity is in part due to a rapid trans-inhibition and a slow, irreversible inactivation of the A system. Neither process is inhibited by cycloheximide or actinomycin D. Alanine antagonizes the growth of CHO-K1 pro cells by preventing proline transport, and alanine-resistant mutants (alar) have been isolated (Moffett et al., Somatic Cell Genet. 9:189-213, 1983). alar2 and alar4 are partial and full constitutive mutants for the A system and have two and six times the Vmax for proline uptake by the A system, respectively. The A system in alar4 is also immune to the co-repressor-induced inactivation. Both alar2 and alar4 phenotypes are recessive. Alar3 shows an increase in Vmax and Km for proline transport through the A system, and this phenotype is codominant. All three mutants have a pleiotropic effect, producing increases in activity of the ASC and P systems of amino acid transport. This increase is not due to an increase in the Na+ gradient. The ASC and P phenotypes behave similarly to the A system in hybrids. A model has been proposed incorporating these results.
Mol Cell Biol 1984 Apr
PMID:Recessive constitutive mutant Chinese hamster ovary cells (CHO-K1) with an altered A system for amino acid transport and the mechanism of gene regulation of the A system. 653 29

It is thought that the C-5 pathway is the major, possibly the sole, route for the formation of delta-aminolevulinic acid for the biosynthesis of tetrapyrroles, including chlorophylls, in higher plants; a route involving 4,5-dioxovalerate as an intermediate followed by transamination to delta-aminolevulinic acid has been supported as one of the C-5 pathways (Granick, S., and Beale, S. I. (1978) Adv. Enzymol. Relat. Areas Mol. Biol. 46, 33-203). A specific aminotransferase for L-alanine and 4,5-dioxovalerate was found in the cucumber seeds. In dark-grown cucumber seedlings, alanine:4,5-dioxovalerate aminotransferase activity in the transitional region between shoot and root was remarkably high compared with that in the cotyledons. The exposure of the dark-grown seedlings to illumination resulted in a rapid and dramatic increase in the activity only in this transitional region. In contrast, the enzyme in the cotyledons, stem, and roots did not respond to illumination. After a 27-h illumination, the enzyme activity in the transitional region was 100-fold higher than that in the cotyledons. Other aminotransferases assayed in the transitional region did not respond to illumination. Alanine:4,5-dioxovalerate aminotransferase in the transitional region was also specific for L-alanine and 4,5-dioxovalerate.
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PMID:Response to light of a specific aminotransferase for delta-aminolevulinate formation in higher plants. 664 46

Alanine and phenylalanine tRNA sequences were amplified by PCR from Arabidopsis thaliana nuclear DNA using degenerate oligonucleotides which introduced specific mutations into the acceptor stem. The aminoacylation of T7 RNA polymerase transcripts of these sequences was investigated in vitro using partially purified bean alanyl- or phenylalanyl-tRNA synthetase. In parallel, the in vivo activity of amber suppressor derivatives of these tRNAs was investigated in transient expression assays in tobacco protoplasts using a beta-glucuronidase (GUS) reporter gene containing a premature amber stop codon. The results show that mutation of the G3:U70 base pair to G3:C70 blocks aminoacylation of plant alanine tRNA, whilst conversion of the G3:C70 pair normally found in plant tRNA(Phe) to G3:U70 enables the mutated tRNA(Phe) to be a good substrate for alanyl-tRNA synthetase and impairs its aminoacylation with phenylalanine. In addition, the amber suppressor derivative of wild-type tRNA(Phe) showed very little suppressor activity in vivo, and was poorly aminoacylated with phenylalanine in vitro, suggesting that the anticodon is a major identity determinant for tRNA(Phe) in plant cells.
Plant Mol Biol 1994 Dec
PMID:Characterization of some major identity elements in plant alanine and phenylalanine transfer RNAs. 753 29

Alanine-scanning mutagenesis on human growth hormone (hGH) identified 5 primary determinants (Arg 8, Asn 12, Arg 16, Asp 112, and Asp 116) for binding to a monoclonal antibody (MAb 3) (Jin L, Fendly BM, Wells JA, 1992, J Mol Biol 226:851-865). To further analyze the energetic importance of residues surrounding these five, we mutated all neighboring residues to alanine in groups of 7-16 (a procedure we call alanine shaving). Even the most extremely mutated variant, with 16 alanine substitutions, caused less than a 10-fold reduction in binding affinity to MAb3. By comparison, mutating any 1 of the 5 primary determinants to alanine caused a 6- to > 500-fold reduction in affinity. Replacing any of the 4 charged residues (Arg 8, Arg 16, Asp 112, and Asp 116) with a homologous residue (i.e., Arg to Lys or Asp to Glu) caused nearly as large a reduction in affinity as the corresponding alanine replacement. It was possible to graft the 5 primary binding determinants onto a nonbinding homologue of hGH, human placental lactogen (hPL), which has 86% sequence identity to hGH. The grafted hPL mutant bound 10-fold less tightly than hGH to MAb3 but bound as well as hGH when 2 additional framework mutations were introduced. Attempts to recover binding affinity by grafting the MAb3 epitope onto more distantly related scaffolds having a similar 4-helix bundle motif, such as human prolactin (23% sequence identity) or granulocyte colony-stimulating factor, were unsuccessful.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Dissecting the energetics of an antibody-antigen interface by alanine shaving and molecular grafting. 753 48


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