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Titolo:
NATURE AND ENVIRONMENT OF THE SULFHYDRYLS OF MEMBRANE-ASSOCIATED D-LACTATE DEHYDROGENASE OF ESCHERICHIA-COLI
Autore:
DOWD SR; PRATT EA; SUN ZY; HO C;
Indirizzi:
CARNEGIE MELLON UNIV,DEPT BIOL SCI,4400 5TH AVE PITTSBURGH PA 15213 CARNEGIE MELLON UNIV,DEPT BIOL SCI PITTSBURGH PA 15213
Titolo Testata:
Biochimica et biophysica acta. Protein structure and molecular enzymology
fascicolo: 2, volume: 1252, anno: 1995,
pagine: 278 - 283
SICI:
0167-4838(1995)1252:2<278:NAEOTS>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; ELLMAN REAGENT; PROTEIN;
Keywords:
D-LACTATE DEHYDROGENASE; ELLMANS REAGENT; SULFHYDRYLS; N-OCTYL-5-DITHIO-2-NITROBENZOIC ACID; (ESCHERICHIA-COLI);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
16
Recensione:
Indirizzi per estratti:
Citazione:
S.R. Dowd et al., "NATURE AND ENVIRONMENT OF THE SULFHYDRYLS OF MEMBRANE-ASSOCIATED D-LACTATE DEHYDROGENASE OF ESCHERICHIA-COLI", Biochimica et biophysica acta. Protein structure and molecular enzymology, 1252(2), 1995, pp. 278-283

Abstract

Ellman's reagent, 5,5'-dithiobis(2-nitrobenzoic acid), has been used to titrate D-lactate dehydrogenase (D-LDH), a respiratory flavoenzyme of Escherichia coli. All six of the possible sulfhydryls titrate in the presence of 2% sodium dodecylsulfate, showing that D-lactate dehydrogenase does not contain any -S-S- bridges. In the native state, only two sulfhydryls are accessible in buffer and only one in the presence of lipid. Single-site mutations of each of the six cysteines of D-lactate dehydrogenase have been prepared. Each of the purified mutant proteins has full activity, demonstrating that an -SH group is not essential to the FAD-driven redox reaction. Ellman's titrations of the mutant proteins have led to the identification of cysteines 65, 146, 156, and256 in the amino-terminal end as those containing the sulfhydryls that are not accessible in buffer or in buffer plus lipid. The cysteine at 422 is titrated only partially in buffer, while in buffer containinglipid, a necessary factor for full enzymatic activity, its sulfhydrylis inaccessible to the reagent. Cysteine 492 has been identified as containing the sulfhydryl that is accessible to the reagent under both conditions.

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Documento generato il 04/12/20 alle ore 22:08:21