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

1. A method is described for the preparation of isolated cells from guinea pig liver. This involved perfusion in situ, in the non-physiological direction, with collagenase. 2. The cell yield was 20--30%, comparable with those from the livers of other species. 3. The ratio of lactate dehydrogenase to glutamate dehydrogenase in the cells was similar to that in vivo, indicating that there was negligible leakage of cytoplasmic enzymes. 4. The concentrations of K+ and adenine nucleotides were initially lower than in the perfused liver; normal values were obtained on incubation, particularly in the presence of substrate. 5. The L-lactate: pyruvate ratio is 16:1, close to established values. The total beta-hydroxybutyrate: acetoacetate ratio indicates that the mitochondrial redox state is more oxidised than in the perfused liver, but the intracellular ratio is similar to that of the intact liver. 6. Rates of gluconeogenesis and ureogenesis, are within the physiological range. Maximal gluconeogeneis from L-lactate was preceded by a lag period. L-lysine stimulated glucose production from L-lactate but did not abolish the lag phase. 7. The effects of aminooxyacetate and octanoate on L-lactate gluconeogenesis were similar to those in the perfused liver.
Mol Cell Biochem 1977 May 31
PMID:Preparation and characterization of isolated parenchymal cells from guinea pig liver. 19 81

The effect of three naturally occurring polyamines (putrescine, spermidine, and spermine) on the activity of rabbit skeletal muscle phosphorylase phosphatase was investigated. Only spermine significantly inhibited the enzyme. The mode of inhibition (ki value of 0.3 mM) of the phosphatase by spermine appears to be different from that caused by divalent metal ions or by other organic cations, such as arginine and lysine esters, since it is noncompetitive with respect to the substrate, phosphorylase a.
Mol Cell Biochem 1977 Apr 12
PMID:Inhibition of rabbit skeletal muscle phosphorylase phosphatase by spermine. 19 99

Chemical modification of pig heart ferricytochrome C by the paramagentic analog of N-acetylimidazole-N-(2,2',5,5'-tetramethyl-3-carboxypyrroline-1-oxyl)-imidazole has been studied. Two main modified preparations, both with the single spin label per molecule, have been isolated by means of chromatography on CM-Sephadex C-25. The study of UV-difference spectra of the SL-preparations versus native Cyt C, the spectrophotometric titration of the tyrosine residues in modified proteins and the study of their reaction with hydroxylamine allow to conclude that one of these preparations (fraction II) is lysine modified Cyt C-SL(Lys)-Cyt C and the other (fraction III) is tyrosine modified protein-SL(Tyr)-Cyt C. From the present results and the data available in literature the most probable location of the modification sites in the three-dimentional structure of Cyt C is Tyr-74 in SL (Tyr)-Cyt C and one of the neighbouring lysil residues Lys 72 or Lys 73 in SL (Lys)-Cyt C on the molecular surface. From the absorbtion and CD-spectra of the modified and native Cyt C in the spectral interval 190--450 nm and from the high resolution PMR data the conclusion has been made that the chemical modification does not alter the immediate vicinity of the heme group and the molecular structure of Cyt C as a whole. Therefore both SL-modified preparations might be useful for the conformational and functional investigations of Cyt C.
Mol Biol (Mosk)
PMID:[Chemical modification of ferricytochrome c by N-(2,2',5,5'-tetramethyl-3-carboxypyrroline-1-oxyl)-imidazole]. 21 5

The influence of a specific histone kinase, phosphorylating lysin-rich histone H1, H2a, H2b on the physico-chemical properties of chromatin from hepatocytes of normal and hepatectomized guinea pigs has been investigated. A cytochemical method has been used which permits to obtain information about the physico-chemical properties of the chromatin in situ, i.e. without its isolation. This approach allows us to evaluate changes in chromatin properties in cell cultures as well as in the intact organism. It is found that the specific histone kinase changes the properties of chromatin in non-dividing cells bringing about an increase of acridine orange binding to the level characteristic for hepatocytes after partial hepatectomy. At the same time the chromatin properties in activated hepatocytes are not changed under the action of the histone kinase. It is concluded that the specific histone kinase, phosphorylating lysine-rich histones can play an important role in the course of chromatin activation in cells stimulated to proliferation.
Mol Biol (Mosk)
PMID:[Influence of histone kinase phosphorylating lysine-rich histones, on the physico-chemical properties of normal hepatocyte chromatin and after partial hepatectomy]. 22 34

The chromatin core particle DNA conformation deduced in broad outline by Finch et al. [Finch, J. T., Lutter, L. C., Rhodes, D., Brown, R. S., Rushton, B., Levitt, M. & Klug, A. (1977) Nature 269, 29-36] can be described in detail using other available experimental results. Histone binding sites compatible with the pattern of pancreatic DNase I digestion (Simpson, R. T. & Whitlock, J. P., Jr. (1976) Cell 9, 347-353; Noll, M. (1977) J. Mol. Biol. 116, 49-71; Lutter, L. C. (1977) J. Mol. Biol. 117, 53-69] lend to core particle DNA pseudosymmetry characteristic of molecular point group D(3). DNA symmetry and pseudosymmetry, in turn, imply equivalence and quasi-equivalence properties of the histone packing arrangement that support the following deductions: (i) One and only one alpha(2)beta(2) histone tetramer, presumably (H3)(2)(H4)(2), can serve as a stable subassembly within the histone octamer. (ii) There is a unique, strand-specific way to assign DNA binding domains to the arginine-rich histones (H3 and H4). (iii) Histones H3 and H4 alone should suffice to impose a supercoiled structure on DNA, as is observed experimentally, because only the tetramer can mimic a screw dislocation and thereby complement the screw symmetry of the DNA supercoil. (iv) The two slightly lysine-rich histones H2A and H2B are probably responsible, each in a different way, for dividing the eukaryotic chromatin fiber into discrete subunits. (v) The proposed arrangement of four distinct proteins appears to be a minimum formal requirement for making nucleosomes; that is, for introducing regularly spaced supercoiled DNA folds without also allowing formation of an indefinitely long (and genetically inert) DNA superhelix.
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PMID:Histone packing in the nucleosome core particle of chromatin. 27 80

Eight strains devoid of homocitrate synthase activity were found among lysine requiring mutants of the yeast Saccharomycopsis lipolytica. Genetic analysis of these strains showed that they were all affected at the same locus LYS 1. Three lines of evidence suggest that this locus defines a structural gene for homocitrate synthase. First, the mutations show various degrees of intragenic complementation; it could be shown in some cases that the hybrid enzyme formed in vivo displayed modified properties in vitro. Second, reversion of some of these mutations can result in a modified enzyme (desensitized). Third, a feedback mutant of homocitrate synthase was directly isolated from the wild type strain, and shown to carry a single mutation at of near LYS 1. We also present here the first attempts at genetic fine mapping in Saccharomycopsis lipolytica.
Mol Gen Genet 1979 May 04
PMID:Evidence for mutations in the structural gene for homocitrate synthase in Saccharomycopsis lipolytica. 28 93

When studying mutants affecting lysyl-tRNA synthetase or tRNAlys (hisT, hisW), a lack of correlation is clearly observed between the amount of lysyl-tRNA and the level of derepression of several lysine biosynthetic enzymes. This exlcudes the possible role of lysyl-tRNA as the specific corepressor of the lysine regulon. However, the level of derepression of DAP-decarboxylase, the last enzyme of the lysine pathway, is very low in the hisT mutant; this indicates that tRNAlys is a secondary effector involved in the regulation of the synthesis of this enzyme.
Mol Gen Genet 1978 Feb 07
PMID:Effect of mutations affecting lysyl-tRNAlys on the regulation of lysine biosynthesis in Escherichia coli. 34 82

Fractionation of acid-soluble proteins from yeast Saccharomyces cerevisiae chromatin by gel electrophoresis suggested the existence of four histonestone fractions--H2a, H2b, H3, H4 and histone H1-like protein. The latter was isolated according to the second method of Johns and extracted with 5% HClO4. Amino acid analysis of the histone H1-like protein showed a moderately high content of basic amino acids, but a much lower ratio of lysine: arginine (approximately 3) than that of the hisone H1 from higher eukaryotes. In addition to histone H1-like protein a protein X was also extracted with 5% HC1O4. The sequence of the electrophoretic mobilities of histone fractions from yeast coincides with those of histone fractions from plants--H4 greater than H3 greater than H2a greater than H2b greater than H1.
Mol Biol (Mosk)
PMID:[Electrophoretic study of the acid soluble proteins of Saccharomyces cerevisiae yeast chromatin]. 35 66

The effect of 2,4-pentandione on the activity of phenylalanyl-tRNA synthetase (Phe-RSase) from E. coli MRE-600 was investigated. It was shown that modification of Phe-RSase with 2,4-pentandione leads to decrease of the aminoacylation rate without an influence on the ATP--[32P]pyrophosphate exchange reaction rate. tRNAPhe protects the enzyme against inactivation. Neither L-Phe and ATP nor the analog fo aminoacyladenylate protects the enzyme against inactivation. There are no changes in Km for amino acid and ATP in the aminoacylation reaction after modification while Km for tRNAPhe decreases three times. The dissociation constant of Phe-RSase: [14C]Phe-tRNA complex increases 4--8 times after modification. It is assumed that there are some lysine residues in Phe-RSase essential for the Phe-RSase-tRNA interaction.
Mol Biol (Mosk)
PMID:[Role of the lysine residues in the phenylalanyl-tRNA synthetase substrates interaction]. 36 1

The influence of modification of Phe-RSase from E. coli MRE-600 by lysine- and arginine-specific reagent 2,4-pentandione on the Phe-RSase.tRNAPhe interactions was investigated. It was shown that modification of Phe-RSase with 2,4-pentandion leads to a decrease of the aminoacylation rate without any influence on the value of Km for tRNAPhe in this reaction and only a slight increase of the value of Kdiss for Phe-RSase.tRNAPhe complex. The log Km (Km-1)--ionic strength dependence for native enzyme and log Kdiss (K-1diss) for native enzyme and two forms modified on arginine and lysine residues were investigated. Results were interpreted quantitatively by Debye--Huckel approximation for two spherical macroions and by Daune approximation assuming that the region of tRNA implicated in ionic interactions is locally a cylindrical polyelectrolyte. It was shown that there are 2-4 electrostatic contacts in Phe-RSase.tRNAPhe interactions in limits of both approximations; modification of arginine residues in Phe-RSase doesn't change the number of electrostatic contacts, modification of lysine residues leads to an increase in the number of contacts. It was assumed that there are lysine residues in Phe-RSase essential for the tRNAPhe recognition. The possibility of participation of negative amino acid residues in electrostatic interactions with tRNAPhe is not excluded.
Mol Biol (Mosk)
PMID:[Influence of the modification of Phe-tRNA synthetase from Escherichia coli by lysine- and arginine-specific reagent on the ionic interactions of the enzyme with tRNA Phe]. 38 96


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