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Titolo:
BIOTRANSFORMATION OF NITROSO AROMATIC-COMPOUNDS AND 2-OXO ACIDS TO N-HYDROXY-N-ARYLACYLAMIDES BY THIAMINE-DEPENDENT ENZYMES IN RAT-LIVER
Autore:
YOSHIOKA T; UEMATSU T;
Indirizzi:
HOKKAIDO INST PHARMACEUT SCI,DEPT HYG CHEM OTARU HOKKAIDO 04702 JAPAN HOKKAIDO INST PHARMACEUT SCI,DEPT HYG CHEM OTARU HOKKAIDO 04702 JAPAN
Titolo Testata:
Drug metabolism and disposition
fascicolo: 7, volume: 26, anno: 1998,
pagine: 705 - 710
SICI:
0090-9556(1998)26:7<705:BONAA2>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
PYRUVATE-DEHYDROGENASE COMPLEX; ALPHA-KETOACID DEHYDROGENASE; ARYLACETAMIDES; TRANSKETOLASE; METABOLISM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
29
Recensione:
Indirizzi per estratti:
Citazione:
T. Yoshioka e T. Uematsu, "BIOTRANSFORMATION OF NITROSO AROMATIC-COMPOUNDS AND 2-OXO ACIDS TO N-HYDROXY-N-ARYLACYLAMIDES BY THIAMINE-DEPENDENT ENZYMES IN RAT-LIVER", Drug metabolism and disposition, 26(7), 1998, pp. 705-710

Abstract

The formation of N-hydroxy-N-arylacylamides from nitroso aromatic compounds and a-ore acids was investigated using rat liver subcellular fractions. Activities were found in both mitochondria and cytosol, except for activities for phenylpyruvate and glyoxylate; the former did notproduce N-hydroxy-N-phenylphenylacetamide and the latter nonenzymatically produced N-hydroxy-N-phenylformamide with nitrosobenzene (NOB), The cytosolic activity of N-hydroxy-N-phenylglycolamide formation was indicated to be due to transketolase, which utilized hydroxypyruvate asa glycolic aldehyde donor to NOB. With mitochondria, 2-oxo acids (including hydroxypyruvate) served as substrates for the biotransformationof NOB to the corresponding N-hydroxy-N-phenylacylamides. The substrate preference was 2-oxobutyrate > pyruvate > 2-oxoisovalerate > 2-oxoisocaproate > 2-oxovalerate > 2-oxo-3-methylvalerate, judging from V-max/half-saturating concentration for mitochondria values. The half-saturating concentrations for NOB were nearly constant. The mitochondrial activity was due to pyruvate dehydrogenase complex and branched-chain 2-oxo acid dehydrogenase complex (BCDHC). By using partially purified BCDHC, pyruvate and 2-oxobutyrate were found to he common substrates for both of the enzymes, and 2-oxoisovalerate was shown to be the most effective substrate for BCDHC. Analysis by the Taft equation indicatedthat the polar effects, rather than the steric effects, of the alkyl groups of 2-oxo acids are important for BCDHC-catalyzed formation of N-hydroxy-N-phenylacylamides. A positive Hammett constant obtained for the formation of N-hydroxy-N-arylisobutyramides indicates that an electron-withdrawing substituent makes the nitroso compounds susceptible to BCDHC-catalyzed biotransformation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 23:41:21