Which of the following enzyme is absent in muscle?: (A) Glucose-1-phosphatase, (B) Glucose 6 phosphatase, (C) Glycogen phosphorylase, (D) Thiophorase
Answer is B. Ref: Harper's Illustrated Biochemistry, 27th edition and Lippincott !s Biochemistry, 3rd editionExplanation:FATE OF MUSCLE GLYCOGENIn muscle, enzyme Glucose - 6- phosphatase is absent.This enzyme catalyzes the final step of glycogenolysis.Hence muscle glycogenolysis does not contribute to blood glucose directly.Glycogen of muscle can only be converted upto glucose - 6 - phosphate as muscle lacks glucose - 6 - phosphatase.Glucose - 6 - phosphate cannot cross the plasma membrane and enters the glycolytic cycle, where it is converted into lactic acid.This lactic acid cross the plasma membrane and reaches liver to form glucose