fatty acid synthesis active sites

AT

acetyl-CoA—ACP transacetylase

MT

malonyl-CoA—ACP transferase

KS

beta-ketoacyl-ACP synthase

KR

beta-ketoacyl-ACP reductase

HD

beta-hydroxyacyl-ACP dehydratase

ER

enoyl-ACP reductase

ACP

acyl carrier protein

ACP

contains that prosthetic group 4’-phosphopantetheine, which is believed to serve as a flexible arm moving rxn intermediates from one active site to the next

the pantothenic acid and beta-mercaptoethylamine groups are identical to CoA

AT

catalyzes the transfer of an acetyl group from acetyl-CoA to the Cys-SH group of beta-ketoacyl-ACP synthase (KS)

MT

catalyzes the transfer of a malonyl group from malonyl-CoA to the Cys-SH group of the acyl carrier protein (ACP)

KS

catalyzes the condensation of the activated acetyl and malonyl groups to form acetoacetyl-ACO and releasing CO2

the C from the released CO2 was the same C from HCO3- introduced to malonyl-CoA

KR

catalyzes the reduction of the carbonyl group at C-3 to form beta-hydroxybutyryl-ACP using NADPH

HD

catalyzes dehydration to form trans-traingle2-butenoyl-ACP

ER

catalyzes reduction of the C-C double bond to form butyryl-ACP using NADPH