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Titolo:
A MULTISTEP PROCESS IS RESPONSIBLE FOR PRODUCT-INDUCED INACTIVATION OF GLUCOSE-FRUCTOSE OXIDOREDUCTASE FROM ZYMOMONAS-MOBILIS
Autore:
FURLINGER M; HALTRICH D; KULBE KD; NIDETZKY B;
Indirizzi:
AGR UNIV VIENNA,INST FOOD TECHNOL,DIV BIOCHEM ENGN,MUTHGASSE 18 A-1190 VIENNA AUSTRIA AGR UNIV VIENNA,INST FOOD TECHNOL,DIV BIOCHEM ENGN A-1190 VIENNA AUSTRIA
Titolo Testata:
European journal of biochemistry
fascicolo: 3, volume: 251, anno: 1998,
pagine: 955 - 963
SICI:
0014-2956(1998)251:3<955:AMPIRF>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
HUMAN ALDOSE REDUCTASE; OXIDATIVE INACTIVATION; CONFORMATIONAL-CHANGES; SUBUNIT DISSOCIATION; ENZYME RHODANESE; AGGREGATION; KINETICS; SORBITOL; DECOMPOSITION; DENATURATION;
Keywords:
GLUCOSE-FRUCTOSE OXIDOREDUCTASE; INACTIVATION; MULTISTEP MECHANISM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
34
Recensione:
Indirizzi per estratti:
Citazione:
M. Furlinger et al., "A MULTISTEP PROCESS IS RESPONSIBLE FOR PRODUCT-INDUCED INACTIVATION OF GLUCOSE-FRUCTOSE OXIDOREDUCTASE FROM ZYMOMONAS-MOBILIS", European journal of biochemistry, 251(3), 1998, pp. 955-963

Abstract

Glucose-fructose oxidoreductase from the bacterium Zymomonas mobilis catalyzes a transhydrogenation reaction in which D-fructose reduction to D-sorbitol is coupled to the oxidation of D-glucose or other aldoses to the corresponding aldonolactones. Tightly protein-bound NADP(H) serves as the cofactor. We found that the interaction of glucose-fructose oxidoreductase with its aldonolactone product triggered a sequential process that affects the protein structure conformationally and chemically and, ultimately, results in an irreversible loss of enzyme activity. (1) Probably as a mechanistic requirement during the catalytic cycle? conformational realignments in glucose-fructose oxidoreductase are induced by binding of the lactone and are manifested by a 1.7-fold increased accessibility to iodide quenching of the fluorescence of theactive-site-bound NADPH, the exposure of one reactive cysteine (likely Cys127) and strongly red-shifted tryptophan fluorescence. (2) As a fast subsequent reaction in vitro, the cysteine residue is deactivated,thus leading to a local: structural destabilization of glucose-fructose oxidoreductase that, without affecting enzyme activity, leads to twofold tryptophan fluorescence as well as the exposure of three furthercysteine residues, (3) The completed deactivation of these cysteines is accompanied by a twofold increase in hydrophobic surface and thus aggregation of the glucose-fructose oxidoreductase tetramer. Aggregation, but not release of the tightly bound NADP(H), ultimately leads to the loss of activity and completes the inactivation of glucose-fructoseoxidoreductase. Apparently small conformational changes at the NADP(H)-binding site of glucose-fructose oxidoreductase trigger high-order protein associations and seem to be thus responsible for an incorrect oligomerization of the enzyme.

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Documento generato il 02/07/20 alle ore 22:24:51