Identification of a novel, thiol-containing co-factor essential for glutathione reductase enzyme activity in trypanosomatids.

Soluble extracts of Trypanosoma brucei, T. cruzi, Leishmania mexicana and Crithidia fasciculata contain a novel enzyme capable of reducing oxidized glutathione by NADPH solely in the presence of an unidentified, dialyzable, heat stable co-factor. Evidence is presented showing that co-factor contains enzymatically reducible thiol group(s), essential for activity. The co-factor is possibly unique to the Kinetoplastida, since dialysate extracts from a wide selection of other organisms would not substitute for trypanosomatid co-factor preparations.