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Titolo:
STOPPED-FLOW KINETIC AND BIOPHYSICAL STUDIES OF MEMBRANE-ASSOCIATED D-LACTATE DEHYDROGENASE OF ESCHERICHIA-COLI
Autore:
SUN ZY; DOWD SR; FELIX C; HYDE JS; HO C;
Indirizzi:
CARNEGIE MELLON UNIV,DEPT BIOL SCI,4400 5TH AVE PITTSBURGH PA 15213 MED COLL WISCONSIN,BIOPHYS RES INST MILWAUKEE WI 53226
Titolo Testata:
Biochimica et biophysica acta. Protein structure and molecular enzymology
fascicolo: 2, volume: 1252, anno: 1995,
pagine: 269 - 277
SICI:
0167-4838(1995)1252:2<269:SKABSO>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; BETA-GALACTOSIDE TRANSPORT; D-LACTIC DEHYDROGENASE; ACTIVE-TRANSPORT; VESICLES; PURIFICATION; MECHANISMS; PHOSPHOLIPIDS; OXIDASE; PROTON;
Keywords:
D-LACTATE DEHYDROGENASE; ELECTRON PARAMAGNETIC RESONANCE; SEMIQUINONE; STOPPED-FLOW KINETICS; (ESCHERICHIA-COLI);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
Z.Y. Sun et al., "STOPPED-FLOW KINETIC AND BIOPHYSICAL STUDIES OF MEMBRANE-ASSOCIATED D-LACTATE DEHYDROGENASE OF ESCHERICHIA-COLI", Biochimica et biophysica acta. Protein structure and molecular enzymology, 1252(2), 1995, pp. 269-277

Abstract

The enzyme kinetics of the FAD-containing membrane-associated D-lactate dehydrogenase (D-LDH) of Escherichia coli have been investigated bystopped-flow spectroscopy. The reduction of D-LDH by the substrate, D-lactate, exhibits a two-stage behavior as observed by the absorbance change for the enzyme-bound FAD. The fast stage with a maximum rate of400 s(-1) represents the rapid formation of the enzyme-substrate complex and the formation of the equilibrium between the oxidized and the reduced enzyme-substrate complexes. The slow stage, which occurs on the order of 0.36 s(-1), represents the slow release of the product, pyruvate, from the reduced enzyme. The formation of a D-LDH semiquinone radical was not observed during the oxidation of D-lactate by D-LDH at 25 degrees C. However, during the subsequent electron transfer from the reduced enzyme to a nitroxide spin-label, a one-electron acceptor, an enzyme intermediate has been observed and identified by both opticaland EPR spectroscopies as an anionic semiquinone. Results from H-1-NMR spectroscopic studies suggest the possible formation of a substrate carbanion when D-lactate is bound at the active site of D-LDH.

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Documento generato il 04/12/20 alle ore 21:52:43