Earlier studies have shown that a long-lived Cr(V) species is produced during the reduction of chromate (Cr(VI)) by microsomes/NADPH, mitochondria, and other cellular constituents and that this Cr(V) species plays a significant role in the mechanism of Cr(VI) toxicity. The present work indicates that this species is a Cr(V) complex involving the diol moieties of NADPH as the ligand. Additionally, ESR spin trapping investigations show that the hydroxyl (.OH) radical is also generated in the reduction process. Hydrogen peroxide (H2O2) enhances the .OH generation but suppresses the Cr(V)-NADPH complex formation. Catalase decreases the .OH radical generation and enhances the Cr(V)-NADPH formation. Measurements under anaerobic atmosphere show decreased .OH radical generation, indicating that during the cellular Cr(VI) reduction process molecular oxygen is reduced to H2O2, which reacts with the Cr(V)-NADPH complex to generate the .OH radical via a Fenton-like mechanism.
|Number of pages
|Archives of Biochemistry and Biophysics
|Published - Nov 1 1991
Bibliographical noteFunding Information:
i This research was supported by the Department of the Interior’s Mineral Institutes Program administered by the Bureau of Mines through the Generic Technology Center for Respirable Dust under Grant G1135142, and NIOSH Grant U60-CCU306149-01-l. ’ To whom correspondence should be addressed.
ASJC Scopus subject areas
- Molecular Biology