Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q9UMR3 (NMR)
 150,598 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

At pH 5.5, sodium trifluoroacetate is a potent competitive inhibitor of porcine elastase (Ki = 2.6 mM) and human leukocyte elastase (Ki = 9.3 mM). For both enzymes the Ki increases strongly with pH. Sodium fluoride is inactive on pancreatic elastase and sodium acetate is a weak inhibitor of this enzyme. Trifluoroethanol inhibits both enzymes but is less active than trifluoroacetate in acidic pH conditions. Bovine trypsin and alpha-chymotrypsin are resistant to the action of sodium trifluoroacetate and trifluoroethanol. The interaction between sodium trifluoroacetate and pancreatic elastase is also demonstrated by 19F NMR spectroscopy. Trifluoroacetyltrialanine is able to displace trifluoroacetate from its complex with pancreatic elastase. In addition, a method using turkey ovomucoid for the active site titration of leukocyte and pancreatic elastase is described.
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PMID:NMR and enzymatic investigation of the interaction between elastase and sodium trifluoroacetate. 2 76

Adenosine 5'-(thiophosphate) AMPS) contains a prochiral phosphorus center. Differentiation of the two diastereotopic oxygens would allow elucidation of the stereochemical course of biological adenylyl transfer reactions. A general method was developed to distinguish between the "pro-R" and "pro-S" oxygens. When we converted the AMPS to the isomer A of adenosine 5'-(1-thiotriphosphate) (ATPalphaS), which is known to have S configuration at Palpha, the pro-R oxygen is incorporated into the bridge position, whereas the pro-S oxygen is located at the nonbridge position. The 31P NMR spectra of the 17O-enriched compounds were used to distinguish between the bridge and nonbridge oxygens based on the decrease in the peak intensity of 31P NMR signals caused by the directly bound 17O isotope. The method was used to elucidate the stereochemical course of acetate activation catalyzed by yeast acetyl coenzyme A (CoA) synthetase. The results indicate that yeast acetyl-CoA synthetase is specific for the isomer B of ATPalphaS and that the nucleophilic displacement proceeds with net inversion of configuration at Palpha of ATPalphaS (B), supporting the "in-line" mechanism.
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PMID:Use of phosphorus-31 nuclear magnetic resonance to distinguish bridge and nonbridge oxygens of oxygen-17-enriched nucleoside triphosphates. Stereochemistry of acetate activation by acetyl coenzyme A synthetase. 3 27

The affinity of bicarboxylate ions (from oxalate to glutarate) for cobalt (II) bovine carbonic anhydrase has been investigated and compared with that of acetate and propionate. The oxalate ion shows a much greater affinity for the enzyme than acetate, whereas the other bicarboxylate ions have very little tendency to bind the enzyme. In every case, and particularly for the oxalate, the apparent affinity constants dramatically increase with decreasing pH. On the basis of the electronic spectra a five-coordinate structure is proposed for all of the above derivatives. Carbon-13 NMR data have been discussed in terms of the oxalate ion chelating the metal ion and/or interacting with the wall of the active cavity.
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PMID:Binding affinity of bicarboxylate ions for cobalt (II) bovine carbonic anhydrase. 10 Jan 45

The microenvironment of histidine-48 of bovine pancreatic ribonuclease A was investigated by proton magnetic resonance spectroscopy (1H NMR) using partially deuterated enzyme in which resolution of the C(2)-H resonance of histidine-48 was simplified. The NMR titration curves at 100 and 250 MHz of histidine-48 of ribonuclease A are discontinuous both for the enzyme alone in 0.3 M chloride and for its complex with cytidine 3'-phosphate. This suggests that titration of histidine-48 occurs only as the result of a slow conformational transition. The sum of the peaks corresponding to histidine-48 in the acid-stable and base-stable forms of the enzyme is less than one proton in the transition region, which indicates that there exists at least one intermediate conformational form of the enzyme. The transition from the acid-stable form to an intermediate form has a pHmid of 5.6, and the transition from an intermediate form to the base-stable form has a pHmid of 6.9. In ribonuclease S and in ribonuclease A in the presence of 0.3 M acetate, the titration curve of histidine-48 is continuous, and the area of the peak is uniform throughout the titration. Proton NMR difference spectra at 100 and 250 MHz reveal a pH-induced conformational change with a pHmid of 5.7 that affects the chemical shift of a single tyrosine residue. This conformational transition is absent in ribonuclease S and is altered in ribonuclease A by the presence of either acetate or cytidine 3'-monophosphate. It is postulated that the same conformational transition is responsible for both the tyrosine perturbation and the disappearance of the histidine-48 peak observed in the acid-stable form of the enzyme. It is proposed that the perturbed tyrosine is tyrosine-25. The transition with pHmid 5.6 is attributed to dissociation of aspartic acid-14, and the transition with pHmid 6.9 is assigned to dissociation of histidine-48. A peak in the aromatic region that moves upfield on addition of the competitive inhibitor cytidine 3'-monophosphate is assigned to a tyrosine, and evidence is presented that this tyrosine is tyrosine-25. Inhibitor binding appears to induce a conformational change in the histidine-48/tyrosine-25 region which is remote from the active site.
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PMID:Correlation proton magnetic resonance studies at 250 MHz of bovine pancreatic ribonuclease. II. pH and inhibitor-induced conformational transitions affecting histidine-48 and one tyrosine residue of ribonuclease A. 24 Mar 91

Time courses of 13C labeling from alanine and ethanol in perfused mouse livers have been followed by NMR. The enrichment at specific carbons of glucose, glutamate, glutamine, aspartate, acetate, acetoacetate, beta-hydroxybutyrate, and lactate has been measured. The specific labeling of glutamate in the presence of labeled alanine and labeled or unlabeled ethanol shows that, under these conditions, alanine enters the tricarboxylic acid cycle almost exclusively through pyruvate carboxylation, whereas ethanol is the exclusive source of acetyl-CoA. In the absence of ethanol, the alanine label flows through both paths. By comparing the scrambling of 13C between C3 and C2 of glutamate it is possible to estimate the mitochondrial fumarase activity; the C6-to-C5 ratios in glucose give the additional scrambling by cytosolic fumarase activity. In addition, the C6-to-C1 and C5-to-C2 ratios in glucose show that there is about 15% flux through the pentose cycle. Finally, the C4-to-C2 ratios in glutamine and glutamate are unequal at any time (the glutamine labels reflect the label distribution in glutamate measured 1 hr earlier), providing a method for studying flow through glutamine synthetase in situ.
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PMID:Effects of ethanol on alanine metabolism in perfused mouse liver studied by 13C NMR. 29

15-beta-hydroxy cyproterone acetate could be identified by thin layer chromatography, mass spectrum, NMR and IR spectrum as a major unconjugated metabolite of cyproterone acetate in plasma and urine of dog, monkey and man. This metabolite has been found to interferein the Mattingly method for the determination of 11-hydroxy-corticosteroids which suggests, that this method is inadequate in controling the adrenal function of subjects treated with cyproterone acetate.
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PMID:Isolation and identification of 15-beta-hydroxy cyproterone acetate as a new metabolite of cyproterone acetate in dog, monkey and man. 41 11

[2,2,2-2H]Ethanol was administered continuously to bile fistula rats for 72 h, with or without (--)-hydroxycitrate. The deuterium labelling of biliary bile acids was determined by GC-MS and 13C NMR. Difference spectra between 2H,1H- and 1H-decoupled 13C NMR spectra showed the presence of partly deuterated methyl and methylene groups in methyl cholate, indicating exchange of deuterium in [2,2,2-2H]ethanol for protium prior to or during incorporation of acetate into the bile acid. The extent of exchange was 20--30% as calculated from the isotopic composition of a fragment ion containing one methyl and one methylene group derived from C-2 of acetate. The exchange was unaffected by (--)-hydroxycitrate, indicating that it was not due to reversible incorporation of deuterated acetate into citrate. About 60% of the acetyl-CoA serving as precursor of cholic and chenodeoxycholic acids were derived from ethanol. This value was not changed by administration of (--)-hydroxycitrate. The half-life time of cholesterol molecules acting as precursors of both bile acids was about 50 h in the presence of (--)-hydroxycitrate, which is about the same as previously found in the absence of the inhibitor.
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PMID:Exchange of methyl hydrogens in ethanol during incorporation in bile acids in vivo. 50 82

Two chemical degradations of clavulanic acid are described which are useful for locating label in 14C-clavulanate. In the first, the beta-hydroxyethylidene side chain of p-bromobenzyl clavulanate is removed by ozonolysis to give p-bromobenzyl (2R, 5R)-3,7-dioxo-4-oxa-1-azabicyclo [3.2.0] heptane-2-carboxylate. The second involves the reaction of p-bromobenzyl clavulanate with dibenzylamine in methanol, to isolate the three beta-lactam carbons as methyl trans-3-(N-N-dibenzyl)amino acrylate. These techniques were used to degrade clavulanic acid derived from fermentations fed with 2-14C-acetate or universally 14C-labelled glycerol. The amount of label retained in the degradation products was in agreement with the distribution of 13C in clavulanic acid derived from 2-13C-acetate, or 1,3-13C2-glycerol, as observed by 13C-NMR.
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PMID:Studies on the biosynthesis of clavulanic acid. II. Chemical degradations of 14C-labelled clavulanic acid. 52 82

Physico-chemical, spectroscopic (UV, CD, ORD, IR-1H-DMR, 19F-NMR, PFT13C-NMR, MS), and chromatographic (TLC, HPLC) properties of 17,21-bis(acetyloxy)-2-bromo-6beta,9-difluoro-11beta-hydroxypregna-1,4-diene-3,20-dione (halopredone acetate; Topicon) are reported. Densitometric and high-pressure liquid chromatographic quantitative analytical methods are described. The usual descriptive data, purity tests, potential impurities arising from the synthesis and stability tests are given.
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PMID:Physico-chemical and analytical studies on Halopredone acetate. 57 29

The biosynthesis of clavulanic acid was investigated by feeding 13C-labelled precursors to Streptomyces clavuligerus fermentations. The resulting samples of clavulanic acid were isolated as the benzyl ester and were examined by 13C NMR spectroscopy for 13C-enrichment. The results showed that the carbon skeleton of 1,3-13C2-glycerol was incorporated intact into the three beta-lactam carbons of clavulanic acid. Studies with 1-13C-acetate, 2-13C-acetate and 1,2-13C2-acetate indicated that the remaining five carbons of clavulanic acid were probably derived from alpha-ketoglutarate. 1-13C-Propionate and 3-13C-propionate were not metabolised via the same route as glycerol, but were probably converted to succinate, via methylmalonyl CoA, and hence via the tricarboxylic acid cycle to the clavulanic acid precursors.
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PMID:Studies on the biosynthesis of clavulanic acid. I. Incorporation of 13C-labelled precursors. 68 Dec 40


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