... octanoyl-CoA.The FAD and the octanoyl-CoA substrate areshown with solid balls in yellow and purple,respectively. a-Helices are labeled alphabetic-ally and, b-strands are numbered consecu-tively, ... domains: N-terminal a-domain, N-terminal b-domain,C-terminal a-domain I, and C-terminal a-domain II(Fig. 7A). The first three domains correspond to the entiresubunit structure of acyl-CoA dehydrogenase, ... fattyacyl-CoA dehydrogenases, ACOs catalyze the initial and rate-determining step of the peroxisomal fatty acidb-oxidation pathway, i.e. a,b-dehydrogenation of acyl-CoA, yielding trans-2-enoyl-CoA...