<prompt> Which of the following enzyme is a constituent of HMP shunt-Glucose-6-phosphataseHexokinaseG-6-P dehydrogenasePhosphorylase  <response>: Ans:C : G-6-P- dehydrogenase.The Hexose MonoPhosphate ShuntIt is also known as Pentose phosphate Pathway PPP. This is alternative Glucose oxidation pathway. Location: Cytoplasm of cells of the liver, adrenal coex, and lactating mammary glands. Substrate: Glucose-6-phosphate. Oxidative poion: Irreversible. Generates two NADPH, which can then be used in fatty acid synthesis and cholesterol synthesis and for maintaining reduced glutathione inside RBCs. Nonoxidative poion: Reversible. Generates intermediate molecules ribose-5-phosphate; glyceraldehyde-3-phosphate; fructose-6-phosphate for nucleotide synthesis and glycolysis. Regulation: Key enzyme in the pentose-phosphate pathway is glucose-6-phosphate dehydrogenase. Levels of glucose-6-phosphate dehydrogenase are increased in the liver and adipose tissue when large amounts ofcarbohydrates are consumed. Glucose-6-phosphate dehydrogenase is stimulated by NADP and inhibited by NADPH and by palmitoyl-CoA pa of the fatty acid synthesis pathway. Purpose: Functions as an alternative route for glucose oxidation that does not directly consume or produce ATP. 