Pentose phosphate pathway
The pentose phosphate pathway, also known as the hexose monophosphate shunt or the phosphogluconate pathway, is a metabolic pathway that occurs in the cytoplasm of cells. It operates parallel to glycolysis and serves multiple purposes, including the generation of NADPH, production of pentose sugars, and providing intermediates for nucleotide synthesis.
The pathway begins with the oxidation of glucose-6-phosphate, catalyzed by the enzyme glucose-6-phosphate dehydrogenase. This reaction produces NADPH and ribulose-5-phosphate. The NADPH generated is an important reducing agent involved in various cellular processes, such as fatty acid synthesis, detoxification of reactive oxygen species, and maintenance of cellular redox balance.
The pentose phosphate pathway branches into two phases: the oxidative phase and the non-oxidative phase. The oxidative phase generates NADPH and produces ribose-5-phosphate, which can be used for nucleotide synthesis. The non-oxidative phase involves a series of reversible reactions that interconvert different sugars, allowing for the production of various intermediates required for cellular metabolism.
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