Kinetic mechanisms of electron bifurcation with electron transfer flavoprotein, NADH, butyryl-CoA dehydrogenase, and ferredoxin reveal a semiquinone cycle.

ABSTRACT: Electron transfer flavoprotein (EtfAB, with α-FAD and β-FAD) and tetrameric butyryl-CoA dehydrogenase (Bcd, with δ-FAD in each subunit) from Acidaminococcus fermentans catalyze electron bifurcation which reduces low potential ferredoxin (Fd) and high potential crotonyl-CoA using NADH as an electron donor. Our previous rapid kinetic studies have demonstrated "pseudo-electron bifurcation" where NADH and two EtfAB molecules generate EtfA_SQB (A_SQ contains α-FAD^•-) and the charge-transfer complex of EtfA_SQB_HQ:NAD⁺ (B_HQ contains β-FADH^-). Since the radical in EtfA_SQB inhibits the further reduction of β-FAD with NADH, the question arises as to how the five components of the complete system interact

SUBMITTER: Sucharitakul J 

PROVIDER: S-EPMC12552937 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature