Rate limiting enzyme in fatty acid synthesis –
Correct Answer: Acety l CoA carboxylase
Description: Ans. is 'c' i.e., Acetyl CoA carboxylase o Production of malonyl-CoA is the initial 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-CoA) a 3- carbon compound Is such activated form.o It is produced by carboxylation of acetyl-CoA, a reaction catalyzed by acetyl-CoA caroxylase.o Acety l-CoA carboxylase requires biotin as a cofactor.o Acetyl-CoA carboxylase is a multienzyme protein containing variable number of identical subunits, each containing biotin carboxylase, biotin carboxyl carrier protein and transcarboxylase.o The reaction also requires HCO- (as a source of CO) and A TPo The reaction takes place in two steps: (i) Carboxylation of biotin involving HCO. and ATP, and (ii) transfer of the carboxyl group to acetyl-CoA to form malonyl-CoA.o This is a typical ATP-dependant carboxylation reaction, with biotin (bound to enzyme) serving as a carrier of carboxyl group.o Since malonyl-CoA is not used in any other metabolic pathway, this reaction is the commited step of fatty acid synthesis i.e. once malonyl-CoA is formed, the cycle will proceed towards fatty acid synthesis only.
Category:
Biochemistry
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now