Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0220723 (PCA)
 4,687 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method for a simultaneous separation of malondialdehyde (MDA), ascorbic acid and adenine nucleotide derivatives in biological samples by ion-pairing high-performance liquid chromatography is presented. The separation is obtained by an LC-18-T 15 cm x 4.6 mm 3 microns particle size column using tetrabutylammonium as the pairing ion. The starting buffer consists of 10 mM tetrabutylammonium hydroxide, 10 mM KH2PO4 plus 1% methanol, pH 7.00. A step gradient is formed using a second buffer consisting of 2.8 mM tetrabutylammonium hydroxide, 100 mM KH2PO4 plus 30% methanol, pH 5.5. Under these chromatographic conditions a highly resolved separation of MDA, ATP, ADP, AMP, adenosine, ascorbic acid, GTP, GDP, IMP, inosine, Hypoxanthine, Xanthine, uric acid, NAD, and NADP can be performed in about 36 min. In addition, the separation of NADH and NADPH can also be obtained; this renders the present method suitable for the detection of these reduced coenzymes in alkaline extracts from tissue samples. Data referring to PCA extracts from ischemic and reperfused isolated rat hearts and from human erythrocytes peroxidized in vitro by a challenge with 1 mM NaN3 and various concentrations of H2O2 are reported. The relevance of this chromatographic method lies in the possibility to determine directly MDA concentrations avoiding the unspecific thiobarbituric acid colorimetric test, any other manipulation of the sample out of the PCA extraction, and any possible coelution of other acid soluble compounds. The simultaneous determination of MDA, ascorbic acid, and of ATP and its degradation products gives the opportunity to correlate, by a single chromatographic run, peroxidative damages with the energy state of the cell which is of great importance in studies of ischemic and reperfused tissues.
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PMID:Simultaneous separation of malondialdehyde, ascorbic acid, and adenine nucleotide derivatives from biological samples by ion-pairing high-performance liquid chromatography. 195 65

As part of an ongoing study of the role of subcellular fractions on the metabolism of nitroxides, we studied the metabolism of a set of five nitroxides in cytosol derived from rat hepatocytes. The nitroxides were chosen to provide information on the effects of the type of charge and the ring on which the nitroxyl group is located. The rates of reduction were fastest for a six-membered positively charged nitroxide ('CAT-1') and slowest for an anionic five-membered ring nitroxide ('PCA'). Changing levels of glutathione, sulphydryl groups in general, NADPH or NADH had little or no effect on the rates of reduction, while the addition of ascorbate oxidase essentially abolished reduction of the nitroxides. The products of reduction by the cytosol were the corresponding hydroxylamines. The overall rates of reduction of neutral or anionic nitroxides were much slower than those observed with intact cells. We conclude that the primary source of metabolism of nitroxides by cytosol is reduction by ascorbate and that under most conditions reduction of nitroxides in the cytosol is not a major factor in the metabolism of nitroxides by cells.
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PMID:Metabolism of nitroxide spin labels in subcellular fractions of rat liver. II. Reduction in the cytosol. 236 85

Geobacter sulfurreducens strain PCA oxidized acetate to CO2 via citric acid cycle reactions during growth with acetate plus fumarate in pure culture, and with acetate plus nitrate in coculture with Wolinella succinogenes. Acetate was activated by succinyl-CoA:acetate CoA-transferase and also via acetate kinase plus phosphotransacetylase. Citrate was formed by citrate synthase. Soluble isocitrate and malate dehydrogenases NADP+ and NAD+, respectively. Oxidation of 2-oxoglutarate was measured as benzyl viologen reduction and strictly CoA-dependent; a low activity was also observed with NADP+. Succinate dehydrogenase and fumarate ductase both were membrane-bound. Succinate oxidation was coupled to NADP+ reduction whereas fumarate reduction was coupled to NADPH and NADH Coupling of succinate oxidation to NADP+ or cytochrome(s) reduction required an ATP-dependent reversed electron transport. Net ATP synthesis proceeded exclusively through electron transport phosphorylation. During fumarate reduction, both NADPH and NADH delivered reducing equivalents into the electron transport chain, which contained a menaquinone. Overall, acetate oxidation with fumarate proceeded through an open loop of citric acid cycle reactions, excluding succinate dehydrogenase, with fumarate reductase as the key reaction for electron delivery, whereas acetate oxidation in the syntrophic coculture required the complete citric acid cycle.
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PMID:Oxidation of acetate through reactions of the citric acid cycle by Geobacter sulfurreducens in pure culture and in syntrophic coculture. 1113 Oct 21

Cytochrome P450 oxidoreductase (POR) is a steroidogenic and drug-metabolizing enzyme. It helps in the NADPH dependent transfer of electrons to cytochrome P450 (CYP) enzymes for their biological activity. In this study, we employed integrative computational approaches to decipher the impact of proline to leucine missense mutation at position 384 (P384L) in the connecting/hinge domain region which is essential for the catalytic activity of POR. Analysis of protein stability using DUET, MUpro, CUPSAT, I-Mutant2.0, iStable and SAAFEC servers predicted that mutation might alter the structural stability of POR. The significant conformational changes induced by the mutation to the POR structure were analyzed by long-range molecular dynamics simulation. The results revealed that missense mutation decreased the conformational stability of POR as compared to wild type (WT). The PCA based FEL analysis described the mutant-specific conformational alterations and dominant motions essential for the biological activity of POR. The LIGPLOT interaction analysis showed the different binding architecture of FMN, FAD, and NADPH as a result of mutation. The increased number of hydrogen bonds in the FEL conformation of WT proved the strong binding of cofactors in the binding pocket as compared to the mutant. The porcupine plot analysis associated with cross-correlation analysis depicted the high-intensity flexible motion exhibited by functionally important FAD and NADPH binding domain regions. The computational findings unravel the impact of mutation at the structural level, which could be helpful in understanding the molecular mechanism of drug metabolism.
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PMID:Insight into the structural and functional analysis of the impact of missense mutation on cytochrome P450 oxidoreductase. 3280 58