a short-chain acyl-CoA + electron-transfer flavoprotein = a short-chain trans-2,3-dehydroacyl-CoA + reduced electron-transfer flavoprotein
bifurcating electron transferring flavoprotein (EtfAf) and butyryl-CoA dehydrogenase (BcdAf) of Acidaminococcus fermentans,which couple the exergonic reduction of crotonyl-CoA to butyryl-CoA to the endergonic reduction of ferredoxin both with NADH. EtfAf contains one FAD (alpha-FAD) in subunit alpha and a second FAD (beta-FAD) in subunit beta. The distance between the two isoalloxazine rings is 18 A. The EtfAf-NAD+ complex structure revealed beta-FAD as acceptor of the hydride of NADH. The formed beta-FADH- is considered as the bifurcating electron donor. As a result of a domain movement, alpha-FAD is able to approach beta-FADH- by about 4 A and to take up one electron yielding a stable anionic semiquinone, beta-FAD-, which donates this electron further to Dh-FAD of BcdAf after a second domain movement. The remaining nonstabilized neutral semiquinone, alpha-FADH-, immediately reduces ferredoxin. Repetition of this process affords a second reduced ferredoxin and Dh-FADH- that converts crotonyl-CoA to butyryl-CoA
a short-chain acyl-CoA + electron-transfer flavoprotein = a short-chain trans-2,3-dehydroacyl-CoA + reduced electron-transfer flavoprotein
bifurcating electron transferring flavoprotein (EtfAf) and butyryl-CoA dehydrogenase (BcdAf) of Acidaminococcus fermentans,which couple the exergonic reduction of crotonyl-CoA to butyryl-CoA to the endergonic reduction of ferredoxin both with NADH. EtfAf contains one FAD (alpha-FAD) in subunit alpha and a second FAD (beta-FAD) in subunit beta. The distance between the two isoalloxazine rings is 18 A. The EtfAf-NAD+ complex structure revealed beta-FAD as acceptor of the hydride of NADH. The formed beta-FADH- is considered as the bifurcating electron donor. As a result of a domain movement, alpha-FAD is able to approach beta-FADH- by about 4 A and to take up one electron yielding a stable anionic semiquinone, beta-FAD-, which donates this electron further to Dh-FAD of BcdAf after a second domain movement. The remaining nonstabilized neutral semiquinone, alpha-FADH-, immediately reduces ferredoxin. Repetition of this process affords a second reduced ferredoxin and Dh-FADH- that converts crotonyl-CoA to butyryl-CoA