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

Incubation of CMP in 2H2O with 0.5M cysteine methyl ester at p2H 5 and 37 degrees C for 24 h resulted in 43% exchange of 5-H to 5-2H. No deamination of the cytosine nucleus was noted during this treatment. Native and denatured DNA samples from calf thymus were treated in 3H2O with cysteine methyl ester at pH 5 and 37 degrees C for 24 h and incorporation of tritium into each DNA base was determined by enzymic digestion of the treated DNA. The order of the specific radioactivity found was cytosine greater than guanine greater than adenine greater than thymine for denatured DNA and guanine greater than adenine approximately cytosine greater than thymine for native DNA. The ratio of radioactivity for denatured/native was 11.6 for cytosine, 1.5 for guanine, 1.8 for adenine and 1.1 for thymine. Hence the incorporation in cytosine under the reaction conditions is preferential for single-stranded, nonhelical regions of DNA. Escherichia coli glutamic acid tRNA II was treated in 3H2O with 1.24 M cysteine methyl ester at pH 5 and 37 degrees C. The 24-h-treated tRNA was digested with ribonuclease T1 and the fragments were fractionated. Each fragment was then digested with ribonuclease T2 into mononucleotides and the radioactivity distribution among the bases was determined. The average radioactivity found for each of the bases of the four major nucleotides was cytosine greater than guanine approximately adenine greater than uracil. The radioactivity in cytosine varied greatly among the RNase T1 fragments, the ratio of the highest to the lowest radioactivity being 18.7. The corresponding value for guanine was 11.1, for adenine 4.73 and for uracil 3.64. Based on the data obtained, it was deduced that in this tRNA the anticodon loop, the dihydrouridine loop and the extra loop were "exposed" under the conditions employed for the labeling. The 5'-terminal cytosine of the anticodon loop was in a "non-exposed" state, a situation similar to that previously reported for E. coli tyrosine tRNA [Cashmore, A. R., Brown, D. M. & Smith, J. D. (1971) J. Mol. Biol. 59, 359-373] and for E. coli formylmethionine tRNA [Goddard J. P.+Schulman L. H. (1972) J. Biol. Chem. 247, 3864-3867]. Both cytosine 48, located at the 3'-terminal of the extra loop, and guanine 15 in the dihydrouridine loop were in an "emposed" state. This finding does not agree with a tRNA model in which this pair of cytosine and guanine, commonly found in tRNA sequences, forms hydrogen bondings. Positions 30--32, 61--64 and 71, which are located in the stems, were found to be strongly "buried".
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PMID:Conformation of Escherichia coli glutamic acid tRNA II as studied by hydrogen-tritium exchange catalyzed by cysteine methyl ester. 0 69

Spin-labeled analogues of vitamin B6: 2, 2, 6, 6-tetramethyl-N-oxylpiperydinyl-4-(5' phosphopyridoxyl)-amine (1) and 2, 2, 6, 6-tetramethyl-N-oxyl-piperydinyl-4-(pyridoxal-5')-phosphate (II) are synthesized. There analogues were shown to interact in the equimolar ratio with the active site of cytosol aspartate transaminase. It was proved by CD-titration of apotransaminase with I and II and by competition between the coenzyme and synthesized analogues. The free valency of spin-labeled coenzymes immediately disappears after interaction with the apoenzyme due to iminoxyl group reduction. The binding of I and II with the apoenzyme is accompanied by oxidation of one of the inner cysteine residues. The reactivation of the modified apoenzyme with PLP is not less than 65% of original transaminase activity. The analysis of space-filling atomic models of synthesized compounds allows to conclude that the distance between the centre of pyridine ring of the coenzyme and the modified thiol group is not more than 8 A.
Mol Biol (Mosk)
PMID:[Interaction of spin-labeled analogues of vitamin B 6 with the active site of apotransaminase]. 17 69

ATP-sulfurylase, cysteine synthase, homocysteine synthase, arylsulfatase and beta-cystathionase in Saccharomycopsis lipolytica are repressed on the addition of methionine, homocysteine or cysteine to the growth medium. The use of appropriate mutants enabled us to demonstrate that the synthesis of these enzymes is regulated by the system involving at least two low-molecular weight effectors--most likely cysteine and methionine (or their close derivatives).
Mol Gen Genet 1979 Jul 02
PMID:Regulation of s-amino acids biosynthesis in Saccharomycopsis lipolytica. 28 1

Isoacceptor species of certain amino acid-specific transfer ribonucleic acids (tRNAs) were fractionated by gel permeation chromatography using Sephadex G-100. The separation is attributed to the 20% ethanol-1% NaCl solvent and to the characteristics of Sephadex. Isoacceptor tRNAs specific for cysteine, arginine, phenylalanine, and histidine were recovered from commercial tRNA of yeast by this method. Highly purified cysteine-specific tRNA, obtained by a method which would not be expected to separate isoacceptor molecules when fractionated by this procedure, was shown to contain two cysteine isoacceptor tRNAs.
Mol Cell Biochem 1977 Mar 21
PMID:Separation of isoacceptor cysteine transfer ribonucleic acids of bakers' yeasts. 32 92

A genetic method was devised to test the hypothesis that in some cysteine or methionine requiring (cym) mutants of Salmonella typhimurium suppression of auxotrophy is due to an insertion at the site of the cym mutation. It was found that suppressed strains have an insertion of about 9kb in the cysCDHIJ region and that in unstable suppressed strains it is the instability of this insertion which results in the segregation of cym auxotrophs.
Mol Gen Genet 1977 Nov 18
PMID:The structure of the cysCDHIJ region in unstable cysteine or methionine requiring mutants of Salmonella typhimurium. 34 Sep 11

A method for selection of constitutive cysB mutation is described which takes advantage of the resistance of cysteine constitutive mutants to 1,2,4-triazole. Since cysM cysK double mutants are cysteine auxotrophs, by selecting for triazole resistance in cysM strains, mutants arising under this condition also should be constitutive for cysteine biosynthesis. Genetic analysis of mutants isolated by this technique showed that their mutational sites are located in the cysB region. Biochemical assays of cysteine enzymes, sulphite reductase and O-acetylserine sulfhydrylase of the mutants showed the derepressed level of these enzymes and the lack or slight repression by 1-cysteine.
Mol Gen Genet 1978 Oct 24
PMID:Method of isolation of cysteine constitutive mutants of the cysteine regulon in Salmonella typhimurium. 36 63

Analysis of published data on the cysteine and half-cystine content of proteins indicates that most intracellular proteins may be classified as sulfhydryl proteins (those containing cysteine but little or no half-cystine) and that such sulfhydryl proteins have a low cysteine content. The mean systeine content found for 32 intracellular mammalian proteins was 1.6% and intracellular proteins of many bacteria have similar or lower values. Extracellular mammalian proteins are primarily disulfide proteins (those containing half-cystine but little or no cysteine) have a high half-cystine content, the mean value found for some 34 extracellular mammalian proteins being 4.1%. This is contrasted with many of the extracellular proteins from facultative bacteria which are cyst(e)ine-free proteins, being lacking in both cysteine and half-cystine. These and related observations are interpreted in terms of the evolution of life in a reducing atmosphere and the subsequent transition to an oxidizing environment. It is suggested that disulfide proteins evolved primarily after the accumulation of oxygen in the atmosphere.
J Mol Evol 1977 Nov 25
PMID:On the cysteine and cystine content of proteins. Differences between intracellular and extracellular proteins. 59 21

Linoleic acid hydroperoxydes (LOOH) containing 13-hydroperoxyoctadeca-9,11-(75%) and 9-hydroperoxyoctadeca-10,12-dienoic acid (25%) were emulsified at pH 6.5. After addition of hemoglobin, ferrous ions, ferric ions, cysteine or ascorbic acid the emulsions were stored 19 hours at 22 degrees C. The decrease in the diene and peroxyde concentrations and the formation of volatile carbonyl compounds were analysed. Ferrous ions and ascorbic acid were the strongest producers of volatile carbonyl compounds. In the presence of 10(-3) Mol ascorbic acid 6 mumol volatile aldehydes arise from 75 mumol LOOH. Hexanal (70 mol-%) was the main component of the aldehyde fraction. For plant foodstuffs the significance of the reaction of fatty acids hydroperoxydes with ascorbic acid for the formation of flavour substances is discussed.
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PMID:[Breakdown of linoeic acid hydroperoxydes. Formation of volatile carbonyl compounds (author's transl)]. 97 38

Nicotinic acid administration, which depletes liver glycogen, leads to an increase of both pyruvate kinase L and phosphoenolypyruvate carboxykinase in liver by a factor of nearly two. The former is not prevented by either cycloheximide or actinomycin D. L-Cysteine, an allosteric inhibitor of pyruvate kinase L, favors gluconeogenesis from lactate in both nicotinic acid treated and starved animals.
Mol Cell Biochem 1976 Nov 30
PMID:Pyruvate kinase activity and gluconeogenesis in rat liver after glycogen depletion with nicotinic acid. 100

50-S ribosomal subunits from the extreme halophilic bacterium, Halobacterium cutirubrum, contain an alanine-rich acidic "A" protein which resembles the L7--L12 multimer (Kaltschmidt and Wittmann, 1970) found in the 50-S ribosomal subunit of Escherichia coli cells. The protein contains 24 mole % alanine and is devoid of histidine, tryptophan and cysteine. Unlike E. coli which has two forms of the "A" protein distinguished solely by the acetylation state of the serine amino terminus. H. cutirubrum 50-S subunits contain only one unsubstituted form of the "A" protein in vivo. However, during purification of ribosomes from cells grown between 25 and 37 degrees C the latter "A" protein undergoes rapid, specific, in vitro enzymatic alteration at its carboxy-terminal end. When the halophile is grown in the temperature range of 40 to 42 degrees C the cleaving enzyme is not active and only one form of the "A" protein is found on the ribosomes.
Mol Gen Genet 1975 Sep 15
PMID:Temperature related alterations in the acidic alanine-rich "A" protein from the 50S ribosomal particle of the extreme halophile, Halobacterium cutirubrum. 110 49


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