3-oxoacyl-[acyl-carrier protein] [CPD:C00685];
[acyl-carrier protein] [CPD:C00229]
This enzyme is responsible for the chain-elongation step of dissociated (type II) fatty-acid biosynthesis, i.e. the addition of two C atoms to the fatty-acid chain. Escherichia coli mutants that lack this enzyme are deficient in unsaturated fatty acids. The enzyme can use fatty acyl thioesters of ACP (C2 to C16) as substrates, as well as fatty acyl thioesters of Co-A (C4 to C16) . The substrate specificity is very similar to that of EC 126.96.36.199, beta-ketoacyl-ACP synthase II, with the exception that the latter enzyme is far more active with palmitoleoyl-ACP (C16Delta9) as substrate, allowing the organism to regulate its fatty-acid composition with changes in temperature [4,5].