Rapid-reaction kinetics of the bifurcating NAD⁺-dependent NADPH:ferredoxin oxidoreductase NfnI from Pyrococcus furiosus.

ABSTRACT: We have investigated the kinetics of NAD⁺-dependent NADPH:ferredoxin oxidoreductase (NfnI), a bifurcating transhydrogenase that takes two electron pairs from NADPH to reduce two ferredoxins and one NAD⁺ through successive bifurcation events. NADPH reduction takes place at the bifurcating FAD of NfnI's large subunit, with high-potential electrons transferred to the [2Fe-2S] cluster and S-FADH of the small subunit, ultimately on to NAD⁺; low-potential electrons are transferred to two [4Fe-4S] clusters of the large subunit and on to ferredoxin. Reduction of NfnI by NADPH goes to completion only at higher pH, with a limiting k_red of 36 ± 1.6 s^-1 and apparent K_d^NADPH of 5 ± 1.2 μM. Reduction of one of the [4Fe-4S] clus

SUBMITTER: Ortiz S 

PROVIDER: S-EPMC10724689 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature