Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Polysomal preparations from isolated pumpkin cotyledons treated with cytokinin [6-benzylaminopurine (BAP), 10 mg/l] were about two-fold more active in the cell-free system of protein synthesis as compared to polysomes from control cotyledons. The time course of 14C-leucine incorporation into protein and its dependence on polysome concentration were studied; sucrose density fractionation have revealed significant differences in polysome distribution between the treated and control cotyledons. All polysomal fractions from BAP-treated cotyledons were more active in protein synthesis than corresponding fractions from control cotyledons. Mixing of BAP-treated and untreated cotyledons before polysome isolation showed that the difference in their activity did not result from isolation procedure. Factors of polysome activation and/or inhibition were tightly bound to polysomes. Treatment of polysomes with 0.175 M KCl reduced markedly their protein-synthesizing activity and abolished the difference between polysomes of BAP-treated and control cotyledons. The initial level of polysome activity could be restored by addition of proteins isolated from the salt wash, but these proteins were not specific in their action. Possible mechanisms of phytohormone action on ribosome activity are discussed. BAP activation of ribosomes in protein synthesis in vitro is fully eliminated by addition of natural inhibitor--abcisic acid--to BAP solution during cotyledons incubation.
Mol Biol (Mosk)
PMID:[Effect of 6-benzylaminopurine on (14C)leucine incorporation into protein in a cell-free system from isolated squash cotyledons]. 61 29

1. Free amino acids were determined in the plasma and in the muscle tissue of 14 patients with chronic uraemia; eight were not on dialysis and six were having regular peritoneal dialysis. The concentration of each amino acid in muscle water was calculated with the chloride method. 2. In both groups of patients there were low intracellular concentrations of threonine, valine, tyrosine and carnosine, and high glycine/valine and phenylalanine/tyrosine ratios. Both groups of patients had increased amounts of 1- and 3-methyl-histidine in plasma and in muscle water. 3. The non-dialysed patients had low intracellular concentrations of lysine, and the dialysed patients had high intracellular concentrations of lysine, isoleucine, leucine and of some of the non-essential amino acids. 4. After peritoneal dialysis for 22 h, the plasma concentration of several amino acids decreased but the intracellular concentrations of most amino acids did not change significantly. 5. Intravenous administration of essential amino acids and histidine during the last 4 h of dialysis increased in muscle the total free amino acids, the ratio of essential to non-essential amino acids and the valine and phenylalanine concentrations. 6. The results demonstrated that the plasma and muscle concentrations of several amino acids are grossly abnormal in chronic uraemia. Non-dialysed and dialysed patients exhibit important differences, especially in the intracellular amino acid patterns. Infusion of essential amino acids may result in enhancement of protein synthesis.
Clin Sci Mol Med 1978 Jan
PMID:Intracellular free amino acids in muscle tissue of patients with chronic uraemia: effect of peritoneal dialysis and infusion of essential amino acids. 62 Apr 93

1. The subcellular distribution of peptidase activities in the normal human jejunum against glycine and leucine homopeptides has been investigated with an analytical fractionation technique. 2. An 8000 g-min supernatant was prepared from homogenates of Crosby capsule biopsy specimens and subjected to isopycnic centrifugation in a Beaufay automatic zonal rotor. 3. The distribution of subcellular organelles in the gradient was established by measurement of organelle-specific marker enzymes. 4. A sensitive fluorimetric assay for glycine peptidase was developed and used for the localization of peptidase activity with peptides composed of from two to five glycine residues as substrates. 5. Glycine peptidase activity was located in the cytosol and in the brush-border membrane but the distribution of activity varied markedly with the chain-length of substrate; the longer the peptide the greater the proportion of activity associated with the brush border. Leucine peptidase showed a similar variation in cytosol--brush border distributions. 6. The results are consistent with concepts that suggest absorption and intracellular hydrolysis of small peptides and brush-border digestion of larger peptides.
Clin Sci Mol Med 1978 Feb
PMID:Subcellular distribution of hydrolase activities for glycine and leucine homopeptides in human jejunum. 62 May 8

1. Glucose absorption, water absorption and dipeptide hydrolase activities have been determined in isolated rat small intestine at 1, 3, 5 and 21 days after a single intraperitoneal injection of 5-fluorouracil. 2. Absorption rates and enzyme activities were elevated 1 day after treatment, but were reduced to 40% of control values at 3 and 5 days. Changes were seen regardless of whether absorption was expressed per unit length or per unit dry weight of intestine. 3. There were highly significant positive correlations between glucose or water absorption rates and peptidase activities, especially in proximal jejunum. The most significant correlation was observed between water absorption rate and jejunal L-Leu-Gly hydrolase activity. 4. Malabsorption may account for some of the gastrointestinal side effects associated with treatment with 5-fluorouracil. Enzyme measurements may be useful as an index of intestinal function.
Clin Sci Mol Med 1978 Apr
PMID:Changes in absorptive and peptide hydrolase activities in rat small intestine after administration of 5-fluorouracil. 63 72

An investigation has been undertaken to determine whether ionizing radiation might engender racemization of optically active amino acids, along with their usual radiolysis. As prototypes, crystalline D- and L-leucine, as well as aqueous solutions of their sodium salts were exposed to the radiation from a 3000 Ci 60Co gamma-ray source. Gamma-ray doses which caused about 68% radiolysis of solid leucine left a residue which was about 5% racemized, while racemization proved even greater at lower doses for the dissolved sodium salts. In aqueous solution both percent degradation and percent racemization of the sodium salts were proportional to gamma-ray dosage within the range employed (1--27 x 10(6) rads). Implications of these observations for the origin of molecular asymmetry by the beta-decay parity violation mechanism are discussed.
J Mol Evol 1978 Jun 20
PMID:Radiolysis, racemization and the origin of molecular asymmetry in the biosphere. 67 65

Protein S5 and S12 were isolated from 30S ribosomal subunits of two E. coli mutants highly resistant to the antibiotic neamine, and of the parental strain. Proteinchemical analyses on these proteins led to the following results: a) In protein S5 the arginine residue in peptide T2 of the parental strain is replaced by glycine in one (nea 314) or serine in the other (nea 319) of the two mutants. b) In protein S12 The proline residue in peptide T15 of the parental strain is replaced by leucine in mutant nea 314 and by glutamine in mutant nea 319. Comparison of these results with those obtained in earlier studies on other mutants with altered ribosomal proteins revealed that the amino acid replacements in neamine resistant mutants and in "revertants" from streptomycin dependence occur at the same amino acid positions of proteins S5 and S12. Therefore it is likely that both types of mutants belong to the same class.
Mol Gen Genet 1975 Dec 23
PMID:Cooperative control of translational fidelity by ribosomal proteins in Escherichia coli. II. Localization of amino acid replacements in proteins S5 and S12 altered in double mutants resistant to neamine. 76 36

Saccharomyces cerevisiae strain 83384-B3 carries the sai-1 mutation which confers sensitivity to S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH). It was shown that the mutant is impermeable to precursors of ribonucleic acid (RNA) and protein during inhibition by SAM (0.2 mM). Inhibition of uptake of adenine and uracil was nearly complete 3 h after growth in the presence of SAM and the uptake of leucine was at least 10-fold lower. The incorporation of 3H-adenine into ribosomal RNA, transfer RNA and heterodisperse RNA, believed to be messenger, was reduced 10-fold when measured after 1 h inhibition. The inhibition of growth was completely reversed by methionine (2.0 mM) in cells previously exposed to SAM for 90 min. The polysome content in cells inhibited by SAM was 25% less than the control after 4 h inhibition. Ribosome synthesis increased only about 40% in the presence of SAM and about 5-fold in the control over an 8 h period. All classes of RNA were synthesized during inhibition.
Mol Gen Genet 1976 Mar 30
PMID:Macromolecule synthesis in a mutant of Saccharomyces cerevisiae inhibited by S-adenosyimethionine. 77 1

An E. coli mutant rpoA109 unable to support the growth of phage P2 produces DNA-dependent RNA polymerase with an altered alpha subunit. Histidine is substituted for leucine in one tryptic peptide from the mutant alpha subunit. The existence of only one rpoA gene within the E. coli chromosome is indicated.
Mol Gen Genet 1976 Apr 23
PMID:Identification of a mutation within the structural gene for the a subunit of DNA-dependent RNA polymerase of E. coli. 77 6

1. Venous blood concentrations of the branched-chain amino acids, valine, leucine and isoleucine, and urinary nitrogen excretion have been measured in sixteen adult males, from 2 h to 7 days after injury, and in four adults after elective skin grafts. 2. In the injured group the concentrations of these amino acids rose significantly 24 h after injury and had doubled at 4 days and remained high; in contrast the skin-graft patients showed no significant change. 3. In those injured patients with initial hyperketonaemia, defined as more than 0-2 mmo1/1, the increase in concentrations of branched-chain amino acids at the fourth and seventh days after injury was significantly less than in those with normoketonaemia, and was accompanied by lower urinary nitrogen excretion throughout the whole period. 4. It is suggested that the changes in the concentration of branched-chain amino acids after injury indicate decreased uptake by muscle or excessive release due to an imbalance between protein synthesis and protein catabolism in this tissue.
Clin Sci Mol Med 1976 May
PMID:Branched-chain amino acids, nitrogen excretion and injury in man. 77 95

In vitro transcription of the trp operon in isolated nucleoids from Escherichia coli was studied. RNA synthesis in this system occurred primarily as a continuation of transcription which had been initiated in vivo; little or no initiation of new RNA chains was observed. Transcription of the trp operon in nucleoids by endogenous RNA polymerase procedded efficiently and ceases sequentially in the order of the gene sequence within the operon. Under these conditions, no appreciable exonuccleolytic digestion of nascent 3H-RNA was found, though some endonucleolytic cleavage was generally seen. Little or no incorporation of 14C-leucine into polypeptides was observed, inspite of tha fact that considerable number of ribosomes and nascent RNA chains were found attached to the isolated nucleoids. The synthesis of trp mRNA continued in the presence of chloramphenicol or fusidic acid, or under conditions where the rebosomal translocation factor G was inactivated. From these and other kinetic studies of trp mRNA synthesis in nucleoids obtained from nonsense strong polar mutants of the trp operon, it was shown that transcription in nucleoids was not connected functionally with transloational processes and thus unable to exhibit polarity effected by a nonsense mutation or by general translational blockage. In studies employing nucleoids from nonsense strong polar mutants of the trp operon, it was demonstrated that RNA polymerase are scantily distributed over the region downstream from the nonsense mutation site of the operon, thereby supporting a notion that in vivo transcription is eventually terminated near the nonsense mutation.
Mol Gen Genet 1976 Nov 17
PMID:In vitro transcription of the tryptophan operon in isolated bacterial nucleoids. 79 65


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