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 hydroxylase activities observed in extracts of Pseudomonas putida ORC after growth on orcinol and resorcinol as sole source of carbon have been purified to homogeneity. Both enzymes were shown to be flavoproteins and to contain approximately 1 mol of FAD for each polypeptide chain, S20,W values for each enzyme are 4.1 +/- 0.1 and are independent of the presence of their aromatic substrates. Molecular weight determinations under native (approximately 68000) and denaturing (approximately 70000) conditions indicated that they are monomeric. The visible absorption spectra identical but the circular dichroic spectra of the two proteins can be distinguished. Although each protein catalyzes the NAD(P)H and O2-dependent hydroxylation of both orcinol and resorcinol, the efficiency of the transformations of the substrates by the two enzymes is radically different; furthermore resorcinol hydroxylase is much more versatile in the aromatic compounds it can utilize as substrates and effectors. Other properties of the enzymes which clearly establish their own identity include their serological characteristics and amino acid composition; the latter property is particularly evident when the quantities of valine and alanine residues are compared. The synthesis of each enzyme is also under different regulatory constraints, being controlled by the substrate used for growth.
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PMID:Bacterial metabolism of resorcinylic compounds: purification and properties of orcinol hydroxylase and resorcinol hydroxylase from Pseudomonas putida ORC. 0 Dec 80

1) Glucose dehydrogenase from Bacillus megaterium has been purified to a specific activity of 550 U per mg protein. The homogeneity of the purified enzyme was demonstrated by gel electrophoresis and isoelectric focusing. 2) The amino acid composition has been determined. 3) The molecular weight of the native enzyme was found to be 116000 by gel permeation chromatography, in good agreement with the values of 120000 and 118000, which were ascertained electrophoretically according to the method of Hedrick and Smith and by density gradient centrifugation, respectively. 4) In the presence of 0.1% sodium dodecylsulfate and 8M urea, the enzyme dissociates into subunits with a molecular weight of 30000 as determined by dodecylsulfate gel electrophoresis. These values indicate that the native enzyme is composed of four polypeptide chains, each probably possessing one coenzyme binding site, which can be concluded from fluorescent titration of the NADH binding sites. 5) In polyacrylamide disc electrophoresis, samples of the purified enzyme exhibit three bands of activity, which present the native (tetrameric) form of glucose dehydrogenase and two monomeric forms (molecular weight 30000), arising under the conditions of pH and ionic strength of this method. 6) The enzyme shows a sharp pH optimum at pH 8.0 in Tris/HCl buffer, and a shift of the pH optimum to pH 9.0 in acetate/borate buffer. The limiting Michaelis constant at pH 9.0 for NAD is 4.5 mM and 47.5 mM for glucose. The dissociation constant for NAD is 0.69 mM. 7) D-Glucose dehydrogenase is highly specific for beta-D-glucose and is capable of using either NAD or NADP. The enzyme is insensitive to sulfhydryl group inhibitors, heavy metal ions and chelating agents.
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PMID:D-glucose dehydrogenase from Bacillus megaterium M 1286: purification, properties and structure. 0 30

The alpha-ketoglutarate dehydrogenase complex of Acetobacter xylinum was purified to homogeneity. It consists of three main polypeptide chains with a total molecular weight of about 2.4 X 10(6). It catalyzes the overall Mg2+ and thiamin pyrophosphate-dependent, NAD+- and CoA-linked oxidative decarboxylation of alpha-ketoglutarate, as well as the partial reactions characteristic of the three enzyme components described for the complex from other sources. Initial velocity studies revealed marked positive cooperativity for the substrate alpha-ketoglutarate (Hill coefficient (nH) = 2.0; concentration of ligand at half-maximum effect (S0.5) = 8 mM). The sigmoidal [alpha-ketoglutarate]-velocity relationship became hyperbolic upon addition of AMP or 3-acetylpyridine adenine dinucleotide (AcPyAD) or in the presence of high concentrations of NAD. S0.5 (alpha-ketoglutarate) decreased to 1 mM, but Vmax was unchanged. Saturation curves for NAD and AMP are sigmoidal (nH = 2) at low alpha-ketoglutarate concentrations and become hyperbolic at high alpha-ketoglutarate concentrations. As judged by S0.5, the relative efficiency of the allosteric effectors is AcPyAD greater than AMP greater than alpha-ketoglutarate- greater than NAD+. Half-maximal changes in nH, S0.5, and activation by AMP occur at a pH significantly different from that of half-maximal activity. A model for the allosteric behavior of the complex is proposed in which the first enzyme component of the complex (E1) is the site for the allosteric interactions and AMP is the primary positive modifier, whereas NAD and AcPyAD act as AMP analogues. The overall reaction is competitively inhibited by NADH with respect to NAD (K1 = 20 micronM) and by succinyl-CoA with respect of CoA (K1 = 3 micronM). The properties of the alpha-ketoglutarate dehydrogenase complex of A. xylinum appear to provide for appropriate partitioning of alpha-ketoglutarate carbon between competing pathways in response to the energy state of the cells.
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PMID:Alpha-ketoglutarate dehydrogenase complex of Acetobacter xylinum. Purification and regulatory properties. 1 9

Pseudomonas aeruginosa toxin (PA toxin) inhibits protein synthesis in a reticulocyte cell-free system. The inhibition requires NAD and results in a block at an elongation step of polypeptide assembly. PA toxin was found to act like diphtheria toxin fragment A. Both toxins catalyze the transfer of radioactivity from nicotinamide(U-14-C)adenine dinucleotide ((14-C)NAD) into covalent linkage with the 100,000 dalton elongation (EF-2) protein. Furthermore, in the presence of a limiting amount of EF-2, excess toxin, and (14-C)NAD, the two toxins were non-additive in the amount of label transferred to EF-3. Unlike free fragment A of diphtheria toxin, the enzymatic activity of PA toxin is heat labile and neutralizable with antibody to PA toxin but not with antibody to fragment A. Although PA and diphtheria toxins have different cellular specificities and molecular properties and produce different clinical symptoms, their intracellular mechanisms of action appear to be identical.
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PMID:NAD-dependent inhibition of protein synthesis by Pseudomonas aeruginosa toxin,. 16 83

A model of the polypeptide backbone of the dimer of glycogen phosphorylase a (EC 2.4.1.1) was built from a 3 A resolution electron density map derived from x-ray diffraction analysis of native tetragonal crystals and two heavy atom isomorphous replacement derivatives. Each identical subunit of the dimer has a compact shape with overall dimensions of 85 X 75 X 55 A and is tightly associated with its 2-fold symmetry related subunit. There are three major excursions of the polypeptide chain of one monomer across the 2-fold axis to make extensive contacts with the other subunit. The active site, of which there are two per dimer, is shared between the two subunits at their interface and comprises a pocket-like region within a "V"-shaped framework of two alpha helices. Within this region are found the binding sites for the substrates, glucose-1-P and arsenate, a competitive inhibitor, UDP-glucose, and the allosteric effector, AMP. The site of metabolic control, Ser-14 phosphate, is hydrogen-bonded to a side chain on the outside of one of the alpha helices forming the active site and is 15 A from the AMP binding site. Maltoheptaose, a glycogen analogue and substrate for these enzymatically active crystals, binds in a second region of interest. Even at concentrations above its Km, when binding is sufficiently tight that all seven glucose moieties may be discerned, the closest of these is 25 A from the glucose-1-P binding site. We suggest that this polysaccharide binding site may represent a storage site whereby phosphorylase is bound to the glycogen particle in the muscle cell. The polypeptide chain in a third region has the same topological structure as has been observed for the nucleotide binding domains in the dehydrogenases. Adenine or adenosine (but not AMP) bind here in a position similar to the adenine ring of NAD in the dehydrogenases while glucose binds 17 A away in an interior crevice near the center of the monomer.
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PMID:Structure of glycogen phosphorylase a at 3.0 A resolution and its ligand binding sites at 6 A. 18 94

The 1030-residue polypeptide chain of the NAD-specific glutamate dehydrogenase of Neurospora crassa was fragmented by treatment with cyanogen bromide. The isolation and sequences of 18 fragments ranging in size from 4 to 51 residues are described. Some of these peptides proved to be cleavage products resulting from hydrolysis at acid-sensitive aspartyl-prolyl bonds. Some overlaps could be deduced on the basis of known sequences of peptides obtained by tryptic hydrolysis.
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PMID:Nicotinamide adenine dinucleotide-specific glutamate dehydrogenase of Neurospora. VI. Isolation and sequences of eighteen fragments from the cyanogen bromide digest. 19 1

The isolation and sequences of several large peptides from cyanogen bromide cleavage of the 1030-residue polypeptide chain of the NAD-specific glutamate dehydrogenase of Neurospora crassa are described. One of these is in the 669-residue sequence of the COOH-terminal end of the protein. The remaining peptides have been aligned in two partial sequences in the NH2-terminal portion of the polypeptide chain.
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PMID:Nicotinamide adenine dinucleotide-specific glutamate dehydrogenase of Neurospora crassa. IX. Isolation and sequences of several large cyanogen bromide peptides. 19 4

The NAD-dependent isocitrate dehydrogenase [threo-D(S)-isocitrate:NAD(+) oxidoreductase (decarboxylating); EC 1.1.1.41] from pig heart is a multisubunit enzyme with a molecular weight of approximately 340,000. Electrophoresis of the enzyme in 10% polyacrylamide gels containing sodium dodecyl sulfate reveals two discrete bands with molecular weights of 41,000 and 39,000. The two bands exhibit approximately equal intensity when stained with Coomassie Blue, Amido Black, and Bromophenol Blue, suggesting that these polypeptide chains are present in equimolar quantities in the native enzyme. The same two-band pattern is observed when the sulfhydryl groups of the enzyme are blocked by alkylation with iodoacetate prior to electrophoresis, indicating that sulfhydryl oxidation is not responsible for the observed heterogeneity. Each of the subunits appears as a single band when eluted from the gel and again subjected to electrophoresis under the same conditions. Isocitrate dehydrogenase contains a total of 41 lysine and arginine residues per average subunit of 40,000 daltons. The observation of approximately 80 peptides upon paper chromatography and high voltage electrophoresis of tryptic digests of the enzyme is consistent with the existence of two distinct polypeptide chains. Dansylation yields two NH(2)-terminal amino acid derivatives: dansyl-phenylalanine and dansyl-alanine. It is concluded that the NAD-specific isocitrate dehydrogenase is composed of equal numbers of two nonidentical subunits.
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PMID:Evidence for the presence of two nonidentical subunits in NAD-dependent isocitrate dehydrogenase of pig heart. 20 34

It is shown that the polypeptide synthetase activity (PS-activity) of chromatin from rat liver is increased 9--21 hrs after partial hepatectomy. Among 9 amino acids studied alanine, methionine, lysine, tyrosine and arginine are not incorporated into the system in question. The highest rate of polymerization is observed in case of glutamic acid. The rate of glutamine, asparagine and glycine incorporation is 7--8 times slower. The PS-activity of chromatin is enhanced by chromatin preincubation with NAD (but not with its analogs). The activation is prevented by thymidine and nicotinamide. Storage of chromatin for 18 hrs at 2--4 degrees C results in a complete loss of PS-activity. Ability of "old" chromatin to incorporate of amino acids may be restored by its preincubation with NAD. Storage of chromatin in the presence of 5 mM cAMP does not decrease the PS-activity. It is assumed that in the system described poly-ADP ribose is an energy source for amino acid activation.
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PMID:[Polypeptide synthetase activity of chromatin from eukaryotic cells]. 21 28

Poly(ADP-ribose) synthetase from calf thymus has been purified to apparent homogeneity by a simple and rapid method with a recovery of 10 to 20%. The enzyme activity absolutely requires the presence of DNA. Histone further stimulates the reaction. The Km for NAD and the maximal velocity at 25 degrees C and pH 8.0 in the presence of both compounds are 55 micron and 1,400 nmol/min/mg, respectively. The sedimentation coefficient (s020,w) of the enzyme is 5.80 S. The molecular weight is calculated to be 108,000 by sedimentation equilibrium method using a partial specific volume of 0.736 ml/g. This value is in good agreement with the molecular weight values of 115,000 and 120,000 determined by gel filtration on Sephadex G-200 and gel electrophoresis in the presence of sodium dodecyl sulfate, respectively. The enzyme is colorless and its absorption spectrum shows a maximum at 280 nm. From a CD spectrum, alpha helical content is estimated to be approximately 30%. The enzyme is a basic protein having a pI value of 9.8 and is rich in lysine rather than arginine. Neutral sugar, phospholipid, and DNA are not detected in the final preparation. These data indicate that the purified enzyme is a simple globular protein composed of a single polypeptide having an approximate molecular weight of 110,000.
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PMID:Purification and characterization of poly(ADP-ribose) synthetase from calf thymus. 21 77


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