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Chauhan, R. and Mande, S.C. (2002) Site-directed mutagenesis reveals a novel catalytic mechanism of Mycobacterium tuberculosis alkylhydroperoxidase C. Biochemical Journal, 367 (Pt 1). pp. 255-61. ISSN 0264-6021

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Abstract

Mycobacterium tuberculosis alkylhydroperoxidase C (AhpC) belongs to the peroxiredoxin family, but unusually contains three cysteine residues in its active site. It is overexpressed in isoniazid-resistant strains of M. tuberculosis. We demonstrate that AhpC is capable of acting as a general antioxidant by protecting a range of substrates including supercoiled DNA. Active-site Cys to Ala mutants show that all three cysteine residues are important for activity. Cys-61 plays a central role in activity and Cys-174 also appears to be crucial. Interestingly, the C174A mutant is inactive, but double mutant C174/176A shows significant revertant activity. Kinetic parameters indicate that the C176A mutant is active, although much less efficient. We suggest that M. tuberculosis AhpC therefore belongs to a novel peroxiredoxin family and might follow a unique disulphide-relay reaction mechanism.

Item Type: Article
Subjects: Genetics
Depositing User: Dr P Divakar
Date Deposited: 02 Jun 2015 06:33
Last Modified: 02 Jun 2015 06:33
URI: http://cdfd.sciencecentral.in/id/eprint/129

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