Rate controlling enzyme of fatty acid synthesis -

Ans. is 'c' i.e., Acetyl-CoA carboxylase o Production of malonyl-CoA is the initialQ and rate limiting step in fatty acid synthesis.o Acetyl-CoA needs to be converted to activated form, which will serve as the donor of carbon units to growing fatty- acid chain.o Malonyl-CoAQ) a 3-carbon compound is such activated form.o It is produced by carboxylation of acetyl-CoA, a reaction catalyzed by acetyl-CoA caroxy laseQ. Acety 1-CoA carboxylase requires biotin as a cofactorQ.o Acetyl-CoA carboxylase is a multienzyme protein containing variable number of identical subunits, each containingbiotin carboxylase, biotin carboxyl carrier protein and transcarboxylase.o The reaction also requires HCO3- (as a source of CO2) and ATPo The reaction takes place in two steps: (i) Carboxylation of biotin involving HCO3 and ATP, and (ii) transfer of the carboxyl group to acetyl-CoA to form malonyl-CoA.