hexose monophosphate shunt (pentose phosphate shunt) A metabolic pathway, alternative to that of glycolysis, of carbohydrate interconversion: hexose-6-phosphate is converted into pentose phosphate and carbon dioxide. The principal functions of the pathway are the production of deoxyribose and ribose sugars for nucleic acid synthesis; the generation of reducing power in the form of NADPH for fatty acid and/or steroid synthesis; and the interconversion of carbohydrates. Parts of the pathway are involved in the Calvin cycle in photosynthesis.

pentose phosphate pathway (pentose shunt) A series of biochemical reactions that results in the conversion of glucose 6-phosphate to ribose 5-phosphate and generates NADPH, which provides reducing power for other metabolic reactions, such as synthesis of fatty acids. Ribose 5-phosphate and its derivatives are components of such molecules as ATP, coenzyme A, NAD, FAD, DNA, and RNA. In plants the pentose phosphate pathway also plays a role in the synthesis of sugars from carbon dioxide. In animals the pathway occurs at various sites, including the liver and adipose tissue.

pentose phosphate pathway See glucose metabolism.