Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cyanobacteria produce multi-L-arginyl-poly (aspartic acid), a high molecular weight (Mr=25 000-125 000) branched polypeptide consisting of a poly(aspartic acid) core with L-arginyl residues peptide bonded to each free carboxyl group of the poly(aspartic acid). An enzyme which will elongate Arg-poly(Asp) has been isolated and purified 92-fold from the filamentous cyanobacterium Anabaena cylindrica. The enzyme incorporates arginine and aspartic acid into Arg-poly(Asp) in a reaction which requires ATP, KCl, MgCl2, and a sulfhydryl reagent. The enzymatic incorporation of arginine is dependent upon the presence of L-aspartic acid but not visa versa, a finding which suggests the order of amino acid addition to the branched polypeptide-aspartic acid is added to the core followed by the attachment of an arginine branch. The elongation of Arg-poly(Asp) in-vitro is insensitive to the addition of protein synthesis inhibitors and to the addition of nucleases. These findings support the notion previosly suggested from in-vivo studies that Arg-poly(Asp) is synthesized via a non-ribosomal route and also demonstrate that amino-acetylated transfer-RNAs play no part in at least one step of the biosynthetic mechanism.
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PMID:The biosynthesis of multi-L-arginyl-poly(L-aspartic acid) in the filamentous cyanobacterium Anabaena cylindrica. 0 11

The glutamine synthetase adenylyltransferase (EC 2.7.7.42), WHIch catalyzes the adenylylation and deadenylylation of glutamine synthetase in E. coli, has been stabilized and purified 2200-fold to apparent homogeneity. Sedimentation and electrophoresis studies show that the native enzyme is a single polypeptide chain of 115,000 +/- 5000 molecular weight with an isoelectric pH (PL) OF 4.98, a sedimentation coefficient (S20.w0) of 5.6S, and a molar frictional coefficient (f/f0) of 1.52. An alpha-helical content of approximately equal to 25% and approximately equal to 28% beta-pleated sheet and approximately equal to 47% random coil structures were estimated from circular dichroism measurements. The amino acid composition of the protein has been determined. The intrinsic tryptophanyl residue flourescence of adenylyltransferase is two fold greater than that of L-tryptophan; this property has been used to monitor ligand-induced conformational changes in the enzyme. Activators of the adenylylation reaction (ATP, L-glutamine, or the E. coli PII regulatory protein) produced an enhancement of fluorescence; alpha-ketoglutarate, an inhibitor of adenylylation and an activator of deadenulylation, caused a net decrease in fluorescence. The adenylytransferase has separate interaction sites for L-glutamine and the regulatory PII protein.
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PMID:Glutamine synthetase adenylyltransferase from Escherichia coli: purification and physical and chemical properties. 0 94

The protein kinase associated with virions of frog virus 3 was purified to apparent homogeneity by ion exchange chromatography and gel filtration. The enzyme protein appeared as a single polypeptide of molecular weight 50,000 to 55,000 as determined by gel filtration, glycerol gradient sedimentation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and comprised approximately 0.4% of the total virion protein. The activity was classified as a cyclic nucleotide-independent protein kinase as it was not effected by cyclic adenosine 3':5'-monophosphate, cyclic guanosine 3':5'-monophosphate, or inhibited by a cyclic nucleotide-dependent protein kinase inhibitor protein, and utilized GTP as well as ATP as a phosphate donor. The greatest rates of phosphorylation were obtained with acidic phosphoprotein substrates such as casein or phosvitin, although potential physiological substrates for this activity included specific virion polypeptides of frog virus.
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PMID:Purification and properties of a virion protein kinase. 0 56

A prodcedure was developed for the purification of the ATP-dependent deoxyribonuclease of Bacillus subtilis 168. It comprises ammonium sulphate fractionation, Sephadex gel filtration, DEAE-cellulose chromatography and gel electrophoresis on a discontinuous polyacrylamide gradient. The enzyme has been obtained in a homogeneous state. Its molecular weight was estimated to be 270000 by disc electrophoresis. Dodecylsulfate-polyacrylamide gel electrophoresis showed the presence of five nonidentical subunits of the following molecular weights: 81000, 70000, 62000, 52500 and 42500. These values give 308000 as the molecular weight of the native enzyme. The pH optimum of the purified enzyme is 9.6. The optimal concentrations of Mg2+ and ATP for exonuclease activity on native B. subtilis DNA were determined. ATP-requirement for hydrolysis of single-stranded DNA is less strigent. The enzyme also possesses high DNA-dependent ATPase activity. The purification procedure was applied to extracts of a mutant devoid of activity for this enzyme (strain GSY 1290). A protein was isolated which is very similar to the active DNAase as regards electrophoretic mobility, reaction with specific antisera and size of four of the subunits. One subunit is missing (Mr 70000) and is replaced by a smaller polypeptide (Mr 565000). The latter results suggest that the mutant is affected in the genetic locus coding for the 70000-Mr subunit.
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PMID:Isolation, subunit structure and properties of the ATP-dependent deoxyribonuclease of Bacillus subtilis. State of the protein in a mutant devoid of activity. 1 60

A deoxyribonuclease has been purified more than 2000-fold from the green algae, Chlamydomonas reinhardii. The enzyme is most active on denatured DNA. Optimum activity is at pH 8.5, in 80 mM Tris-HCl buffer and 2 mM CaCl2. Other divalent cations can replace Ca2+ with varying lower efficiency. EDTA and inorganic phosphate are strongly inhibitory, while ATP and high concentrations of 2-mercaptoethanol are slightly inhibitory. The molecular weight is approximately 35 000, the Stokes radius is 2.7 nm, and the sedimentation coefficient 2.8 S. It is a single polypeptide chain, and the frictional ratio of 1.27 suggests it is only slightly asymetrical. The isoelectric point is 9.5. This enzyme has been termed exonuclease 1.
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PMID:A deoxyribonuclease from Chlamydomonas reinhardii. 1. Purification and properties. 1 43

Motile extracts have been prepared from Dictyostelium discoideum by homogenization and differential centrifugation at 4 degrees C in a stabilization solution (60). These extracts gelled on warming to 25 degrees Celsius and contracted in response to micromolar Ca++ or a pH in excess of 7.0. Optimal gelation occurred in a solution containing 2.5 mM ethylene glycol-bis (beta-aminoethyl ether)N,N,N',N'-tetraacetate (EGTA), 2.5 mM piperazine-N-N'-bis [2-ethane sulfonic acid] (PIPES), 1 mM MgC1(2), 1 mM ATP, and 20 mM KCI at ph 7.0 (relaxation solution), while micromolar levels of Ca++ inhibited gelation. Conditions that solated the gel elicited contraction of extracts containing myosin. This was true regardless of whether chemical (micromolar Ca++, pH >7.0, cytochalasin B, elevated concentrations of KCI, MgC1(2), and sucrose) or physical (pressure, mechanical stress, and cold) means were used to induce solation. Myosin was definitely required for contraction. During Ca++-or pH-elicited contraction: (a) actin, myosin, and a 95,000-dalton polypeptide were concentrated in the contracted extract; (b) the gelation activity was recovered in the material sqeezed out the contracting extract;(c) electron microscopy demonstrated that the number of free, recognizable F-actin filaments increased; (d) the actomyosin MgATPase activity was stimulated by 4- to 10-fold. In the absense of myosin the Dictyostelium extract did not contract, while gelation proceeded normally. During solation of the gel in the absense of myosin: (a) electron microscopy demonstrated that the number of free, recognizable F- actin filaments increased; (b) solation-dependent contraction of the extract and the Ca++-stimulated MgATPase activity were reconstituted by adding puried Dictyostelium myosin. Actin purified from the Dictyostelium extract did not gel (at 2 mg/ml), while low concentrations of actin (0.7-2 mg/ml) that contained several contaminating components underwent rapid Ca++ regulated gelation. These results indicated : (a) gelation in Dictyostelium extracts involves a specific Ca++-sensitive interaction between actin and several other components; (b) myosin is an absolute requirement for contraction of the extract; (c) actin-myosin interactions capable of producing force for movement are prevented in the gel, while solation of the gel by either physical or chemical means results in the release of F-actin capable of interaction with myosin and subsequent contraction. The effectiveness of physical agents in producting contraction suggests that the regulation of contraction by the gel is structural in nature.
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PMID:The contractile basis of amoeboid movement. V. The control of gelation, solation, and contraction in extracts from Dictyostelium discoideum. 2 Apr 47

Studies have been made on thermal synthesis of peptides containing amino acids (glycine, alanine, leucine, threonine, and histidine) and succinic acid. The synthetic products were found to be heterogeneous, comprising mostly linear polymers. In the peptides obtained, the ratio between individual amino acids differed from the initial one. It was demonstrated that glycine exhibits high capacity for polymerization. At the same time, most polymerized peptides contained large amounts of leucine. In hydrolyzates of some of the peptides, a new non-identified amino acid was found which was formed from threonine. The peptides obtained exhibited catalytic properties: they hydrolyzed-p-nitrophenyl-phosphate, increased the breakdown of ascorbic acid by hydrogen peroxide and splitted inorganic phosphate from ATP. These activities depended on PH of the medium, the duration of action and substrate concentration. Synthetic products which contained threonine residues, exhibited higher activities as compared to other peptides. The data obtained reveal a possibility of incorporating the organic acids into polypeptide chains during abiogenic synthesis of biologically active substances. Such compounds with non-specific catalytic properties could serve as one of the steps in evolution of biocatalyzers.
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PMID:[Abiotic synthesis of peptides containing a dicarboxylic acid and their catalytic properties]. 3 Oct 45

The phosphorylation of spectrin polypeptide 2 is thought to be involved in the metabolically dependent regulation of red cell shape and deformability. Spectrin phosphorylation is not affected by cAMP. The reaction in isolated membranes resembles the cAMP-independent, salt-stimulated phosphorylation of an exogenous substrate, casein, by enzyme(s) present both in isolated membranes and cytoplasmic extracts. Spectrin kinase is selectively eluted from membranes by 0.5 M NaCl and co-fractionates with eluted casein kinase. Phosphorylation of band 3 in the membrane is inhibited by salt, but the band 3 kinase is otherwise indistinguishable operationally from spectrin kinase. The membrane-bound casein (spectrin) kinase is not eluted efficiently with spectrin at low ionic strength; about 80% of the activity is apparently bound at sites (perhaps on or near band 3) other than spectrin. Partitioning of casein kinase between cytoplasm and membrane is metabolically dependent; the proportion of casein kinase on the membrane can range from 25% to 75%, but for fresh cells is normally about 40%. Dephosphorylation of phosphorylated spectrin has not been studied intensively. Slow release of 32Pi from [32P] spectrin on the membrane can be demonstrated, but phosphatase activity measured against solubilized [32P] spectrin is concentrated in the cytoplasm. The crude cytoplasmic phosphospectrin phosphatase is inhibited by various anions--notably, ATP and 2,3-DPG at physiological concentrations. Regulation of spectrin phosphorylation in intact cells has not been studied. We speculate that spectrin phosphorylation state may be regulated 1) by metabolic intermediates and other internal chemical signals that modulate kinase and phosphatase activities per se or determine their intracellular localization and 2) by membrane deformation that alters enzyme-spectrin interaction locally. Progress in the isolation and characterization of spectrin kinase and phosphospectrin phosphatase should lead to the resolution of major questions raised by previous work: the relationships between membrane-bound and cytoplasmic forms of the enzymes, the nature of their physical interactions with the membrane, and the regulation of their activities in defined cell-free systems.
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PMID:Phosphorylation and dephosphorylation of spectrin. 3 38

We have studied the effects of adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase on the phosphorylative and functional modification of bovine adrenal tyrosine hydroxylase. Incubation of partially purified tyrosine hydroxylase with cAMP-dependent protein kinase in the presence of [gamma32P]ATP and 5 micron cAMP led to a 3- to 5-fold activation of tyrosine hydroxylase and to incorporation of [32P]phosphate into protein. When tyrosine hydroxylase preparations activated by exposure to enzymatic phosphorylating conditions were analyzed by sucrose density gradient centrifugation, polyacrylamide gel electrophoresis, and gel electrofocusing, the radioactivity of 32P was coincident with the activity of tyrosine hydroxylase, suggesting incorporation of 32P from [gamma-32P]ATP into tyrosine hydroxylase. Polyacrylamide gel electrophoresis of the phosphorylated tyrosine hydroxylase preparation in the presence of 0.1% sodium dodecyl sulfate revealed that the 60,000-dalton polypeptide subunit of tyrosine hydroxylase served as the phosphate acceptor.
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PMID:In vitro phosphorylation of bovine adrenal tyrosine hydroxylase by adenosine 3':5'-monophosphate-dependent protein kinase. 3 70

Arginyl-tRNA synthetase from Escherichia coli K12 has been purified more than 1000-fold with a recovery of 17%. The enzyme consists of a single polypeptide chain of about 60 000 molecular weight and has only one cysteine residue which is essential for enzymatic activity. Transfer ribonucleic acid completely protects the enzyme against inactivation by p-hydroxymercuriben zoate. The enzyme catalyzes the esterification of 5000 nmol of arginine to transfer ribonucleic acid in 1 min/mg of protein at 37 degrees C and pH 7.4. One mole of ATP is consumed for each mole of arginyl-tRNA formed. The sequence of substrate binding has been investigated by using initial velocity experiments and dead-end and product inhibition studies. The kinetic patterns are consistent with a random addition of substrates with all steps in rapid equilibrium except for the interconversion of the cental quaternary complexes. The dissociation constants of the different enzyme-substrate complexes and of the complexes with the dead-end inhibitors homoarginine and 8-azido-ATP have been calculated on this basis. Binding of ATP to the enzyme is influenced by tRNA and vice versa.
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PMID:Arginyl-tRNA synthetase from Escherichia coli K12. Purification, properties, and sequence of substrate addition. 3 99


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