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)

The in vitro synthesis of the mini R1-factor, Rsc11, was achieved using a soluble Escherichia coli cell-extract system. Triton X-100 lysates of the K12 strain 1101 (Rsc11) fractionated by Sephadex G25 chromatography supported the incorporation of labeled deoxyribonucleotides into covalently-closed circular (30S) and open-circular (25S) plasmid DNA as well as other molecules of various sizes. DNA synthesis required the presence of all four ribonucleotides and was rifampicin sensitive. Pulse-chase experiments indicated that this reaction is discontinuous. A dependence on ATP and sensitivity to nalidixic acid suggested this system capable of the replicative synthesis of Rsc11 DNA. Density-shift analysis confirmed this. In addition to hybrid, fully-heavy plasmid supercoils were synthesized indicating that more than one round of replication was completed. Approximately one-third of the molecules available to the system participate in this reaction.
Mol Gen Genet 1979 Feb 16
PMID:In vitro system for the replication of the mini R1 factor Rsc11. 37 16

E. coli DNA dependent RNA polymerase was modified by diethylpyrocarbonate. Optical and kinetic properties of the reaction were studied. More than 90% of RNA polymerase activity is inhibited by introduction of 9--11 ethoxyformyl groups per enzyme molecule without loss of its ability to bind DNA template. Furthermore the modified enzyme is able to form tight complexes with DNA and to compete with native enzyme for the formation of rifampicin-resistant complex. The ratio of the complex formation constants for the native and modified enzyme was determined to be equal to 10. The enzyme modified to such extent loses the activity in DNA dependent RNA as well as pppApU synthesis. Vmax value rather than Km value for both ATP and UTP decreases following the modification reaction. Incubation of the enzyme modified to the 10% of residual activity with 0.2 M hydroxylamine for 2 hours results in restoration of RNA polymerase activity. Most but not all of the modified histidyl residues restore their native structure. Two of 13 histidyl residues were modified irreversibly due to Bamberger's cleavage reaction, but these two residues were found to be unessential for RNA polymerase activity. Reaction with higher concentration of the diethylpyrocarbonate induces modification of more than 15--20 histidyl residues and leads to irreversible inactivation of the enzyme. Nevertheless the modification of the additional histidyl redidues was reversible as well as the modification of the first 11 residues. RNA polymerase modified to such extent loses the ability to bind DNA. Preformation of the initiated ternary complex of RNA polymerase with template and product fails to protect the enzyme from reversible inactivation at a low reagent concentration, but markedly decreases the rate of the irreversible and unspecific modification of sulfhydryl or amino groups of the enzyme. Reaction with the ternary complex results in reversible inactivation of the enzyme with respect to elongation of RNA chains as well as the pyrophosphate exchange reaction. The complex itself was, however, completely stable under the reaction conditions and the enzyme subunit structure was also conserved after the reaction. Evidently, the mild modification of the histidyl residues with diethylpyrocarbonate selectively inhibits RNA chain elongation.
Mol Biol (Mosk)
PMID:[Modification of the RNA-polymerase of Escherichia coli by diethylpyrocarbonate]. 37 63

The influence of some ATP analogs with the modified ribose residues on the transcription in vitro was studied. It was shown that all analogs are weak inhibitors competing with in RNA synthesis. Under certain conditions (ionic strength = 0.13, 25 degrees C) the only effective inhibitor of RNA synthesis 3'-O-methyl-ATP arrests reaction irreversibly. Perhaps as a result of its incorporation into the terminal position of the growing RNA chain. The increase of the temperature and of the ionic strength results in changes of the character of inhibition: 3'-O-methyl-ATP becomes (like other analogues) a reversible competitive inhibitor with a Ki = 4 . 10(-5) M. Some speculations concerning the mechanism of inhibition are discussed.
Mol Biol (Mosk)
PMID:[ATP analogs in the RNA-polymerase reaction]. 37 50

A procedure for the large-scale isolation of leucyl-tRNA synthetase from E. cole MRE 600 is described: The enzyme was purified about 320-fold to homogeneity by precipitation with cetyl-trimethyl-ammonium bromide, two consecutive chromatographies on DEAE-cellulose and three on hydroxyapatite with an over-all yield of 4%. The molecular weight of leucyl-tRNA synthetase from E. coli MRE 600 was found to be 99 000 daltons. Bindings studies by ultracentrifugation and equilibrium partition showed that the enzyme binds leucine, leucyl-adenylate and tRNA Leu, each in a 1 : 1 stoichiometry. For ATP only a very weak binding to the enzyme could be observed, which did not allow the evaluation of the complex stoichiometry. The presence of ATP was not required for the binding of leucine or tRNA to leucyl-tRNA synthetase from E. coli MRE 600.
Mol Cell Biochem 1979 Apr 02
PMID:Isolation and binding properties of leucyl-tRNA synthetase from Escherichia coli MRE 600. 37 93

In Saccharomyces cerevisiae, a small proportion of the glucose-6-P dehydrogenase activity is firmly associated with the mitochondrial fraction and is not removed by repeated washing or density-gradient centrifugation. However, the enzyme is released by sonic disruption. Mitochondrial glucose-6-P dehydrogenase that is released by sonication and partially purified has been found to be similar to cytosol glucose-6-P dehydrogenase with respect to electrophoretic mobility, isoelectric point, pH optimum, molecular size, and apparent KM's for NADP+ and glucose-6-P. These results indicate that a single species of glucose-6-P dehydrogenase is synthesized in S. cerevisiae and that the enzyme has more than one intracellular location. Mitochondrial glucose-6-P dehydrogenase may be a source of intramitochondrial NADPH and may function with hexokinase and transhydrogenase to provide a pathway for glucose oxidation that is coupled to the synthesis of mitochondrial ATP. A constant proportion of total glucose-6-P dehydrogenase activity remains compartmented in the mitochondrial fraction throughout the growth cycle.
Mol Cell Biochem 1979 May 06
PMID:Mitochondrial glucose-6-phosphate dehydrogenase from Saccharomyces cerevisiae. 38 93

ATP gamma-(p-azidoanilidate) (1) and ATP gamma-(p-azidobenzyl)-methylanilidate (2) were shown to be competitive inhibitors for ATP and amino acid in tRNA aminoacylation catalyzed by E. coli MRE-600 phenylalanyl-tRNA synthetase (E.C.6.1.1.20). Low concentration (10(-5)--10(-6) M) of either ATP, gamma-anilidate or GMP stimulates the aminoacylation of tRNA suggesting their interaction with some nucleotide binding sites of the enzyme other than catalytic ones. Covalent photobinding of (1) to the enzyme does not inhibit aminoacylation, nor does it prevent nucleotides from activating the enzyme. UV-irradiation of the synthetase in the presence of (2) results in complete inactivation of the enzyme which can be prevented by phenylalanine or phenylalanine-ATP to save 50% of the enzyme activity but not ATP and tRNA. The photobinding of (2) to the enzyme in the presence of phenylalanine and ATP removes the activation of the enzyme by nucleotides suggesting that both the catalytic and effector sites of the synthetase are blocked in the same manner by compound (2).
Mol Biol (Mosk)
PMID:[Influence of the structure of photoreactive ATP analogs on the affinity modification of phenylalanyl-tRNA synsthetase. Modification of the enzyme at two types of nucleotide sites]. 38 88

The kinetic and regulatory properties of purified rat heart AMP deaminase were investigated. In the presence of 100 mM KCl, the enzyme exhibited a slightly sigmoid-shaped plot of reaction rate, vs. substrate concentration, which shifted to a more hyperbolic form when ATP, ADP or GTP were added. ATP was the most potent activator of the enzyme, whereas GTP at low (less than 0.25 mM) concentrations increased the enzyme activity. The activation effect was negligible at higher concentrations of GTP. The calculated value of K0.5 of approx. 3 mM for unactivated enzyme decrased to approx. 0.6 mM and 1.1 mM when 0.5 mM ATP or 1.5 mM ADP were present in the incubation mixture, respectively. The theoretical model (Monod, J., Wyman, J. and Changeux, J.P. (1965) J. Mol. Biol. 12, 88-118) gave a partial explanation of these results.
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PMID:Regulatory properties of rat heart AMP deaminase. 44 47

Glucose-6-phosphate dehydrogenase was purified to homogeneity from testes and kidneys of the inbred strain of mice (DBA/2J) by a simple two-step affinity column procedure. This involved the sequential application of 8-(6-aminohexyl)-amino-AMP- and -2', 5'-ADP-Sepharose columns and biospecific elution with NADP+ in both steps. The molecular and biochemical properties of the purified enzyme were studied in detail. These include the molecular weight determination, amino acid composition, steady-state kinetics, inactivation by high temperature, urea and iodoacetate, and immunology. The purified enzyme from mouse kidneys or testes was shown to be a tetramer with a molecular weight of 220,000. The enzyme is highly specific for glucose-6-phosphate, exhibits almost no activity with NAD+ as a coenzyme and is little inhibited by AMP or ATP. Michaelis constants for glucose-6-phosphate and NADP+ were determined to be 50 microM and 10 microM respectively. NADPH is a competitive inhibitor of NADP+ and has a Ki of 18 microM. Rabbit antisera against glucose-6-phosphate dehydrogenase were raised. The antisera also cross-react with the same enzyme from human and guinea pig.
Mol Cell Biochem 1979 Mar 19
PMID:Purification and characterization of mouse glucose 6-phosphate dehydrogenase. 46 Jan 73

The distance between fluorescein mercuric acetate (FMA), attached to the HS-group of Fe- and Mo-Fe-protein, and the nearest iron-sulphur cluster (ISC) was determined. For Fe-protein the distance was 18--20 A and for Mo-Fe-protein 12--14 A. The distance between Fe-protein FMA and the nearest Mo-protein ISC determined by complementation of the labelled Fe-protein and native Mo-Fe-protein was 14--16 A. The distance between MO-OFe-protein ISC and complement Fe-protein ISC was 18--20 A. A te-protein ISC permitted to suppose that the electron was transfered from Fe-protein ISC to Mo-Fe-protein ISC by the contact of the ISC or with the help of ATP molecule.
Mol Biol (Mosk)
PMID:[Estimation of the distance between the iron-sulfur cluster of Fe-protein and the nearest iron-sulfur cluster of Mo-Fe-protein of nitrogenase on the basis of the inductive-resonance theory of energy transfer]. 50 57

Partially purified flounder muscle (Pseudopleuronectus americanus) glyceraldehyde 3-phosphate dehydrogenase was immobilized on cyanogen bromide-activated Sepharose. The catalytic properties of the immobilized preparation were studied to determine if immobilization alters the kinetic properties of the native holoenzyme. The results indicate that the pH activity profile of immobilized glyceraldehyde 3-phosphate dehydrogenase did not differ from that of the native enzyme. The Michaelis constants (Km) for NAD and glyceraldehyde 3-phosphate were somewhat altered. The enzyme stability toward various inactivation treatments in the presence and absence of NAD was characterized and compared to that of he native enzyme. When either form of the enzyme was incubated with urea at concentrations greater than 2M, inactivation occurred very rapidly. Incubation in 0.1% trypsin for 60 minutes decreased the activity of immobilized glyceraldehyde 3-phosphate dehydrogenase by 45% and of the native soluble enzyme by 70%. The immobilized enzyme also exhibited considerably more stability than the native soluble enzyme when exposed to a temperature of 50 degrees or to 20 mM ATP. In all cases NAD either greatly reduced the rate of inactivation or completely protected the enzyme from inactivation.
Mol Cell Biochem 1978 Nov 16
PMID:Immobilized flounder muscle glyceraldehyde 3-phosphate dehydrogenase. 56 63


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