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Titolo:
PROPERTIES OF THE ARSENATE REDUCTASE OF PLASMID R773
Autore:
GLADYSHEVA TB; ODEN KL; ROSEN BP;
Indirizzi:
WAYNE STATE UNIV,SCH MED,DEPT BIOCHEM,540 E CANFIELD AVE DETROIT MI 48201 WAYNE STATE UNIV,SCH MED,DEPT BIOCHEM DETROIT MI 48201
Titolo Testata:
Biochemistry
fascicolo: 23, volume: 33, anno: 1994,
pagine: 7288 - 7293
SICI:
0006-2960(1994)33:23<7288:POTARO>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
GLUTATHIONE-DEPENDENT SYNTHESIS; ARSENICAL RESISTANCE OPERON; ESCHERICHIA-COLI; STAPHYLOCOCCUS-AUREUS; ARSC PROTEIN; ANION PUMP; DEOXYRIBONUCLEOTIDES; PURIFICATION; GLUTAREDOXIN; MECHANISM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
27
Recensione:
Indirizzi per estratti:
Citazione:
T.B. Gladysheva et al., "PROPERTIES OF THE ARSENATE REDUCTASE OF PLASMID R773", Biochemistry, 33(23), 1994, pp. 7288-7293

Abstract

Resistance to toxic oxyanions in Escherichia coli is conferred by thears operon carried on plasmid R773. The gene products of this operon catalyze extrusion of antimonials and arsenicals from cells of E. coli, thus providing resistance to those toxic oxyanions. In addition, resistance to arsenate is conferred by the product of the arsC gene. In this report, purified ArsC protein was shown to catalyze reduction of arsenate to arsenite. The enzymatic activity of the ArsC protein required glutaredoxin as a source of reducing equivalents. Other reductants,including glutathione and thioredoxin, were not effective electron donors. A spectrophotometric assay was devised in which arsenate reduction was coupled to NADPH oxidation. The results obtained with the coupled assay corresponded to those found by direct reduction of radioactive arsenate to arsenite. The only substrate of the reaction was arsenate (K-m = 8 mM); other oxyanions including phosphate, sulfate, and antimonate were not reduced. Phosphate and sulfate were weak inhibitors, while the product, arsenite, was a stronger inhibitor (K-i = 0.1 mM). Arsenate reductase activity exhibited a pH optimum of 6.3-6.8. These results indicate that the ArsC protein is a novel reductase, and elucidation of its enzymatic mechanism should be of interest.

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Documento generato il 30/11/20 alle ore 07:15:52