Hexose Monophosphate Shuntis an alternate route forthe oxidation of glucose where ATP (energy) isneither produced nor utilized.The pentose phosphate pathway takes place entirelywithin the cytoplasm (because NADP+ is used as ahydrogen acceptor) and is also known as the hexosemonophosphate shunt or phosphogluconate pathwayIs basically used for the synthesis of NADPH and DriboseTwo phases: The irreversible oxidativephase: generates NADPHwhich is required for manybiosynthetic pathways andfor detoxification of reactiveoxygen species.The nonoxidative phase:interconverts C3, C4, C5, C6and C7 monosaccharides toproduce ribose5P fornucleotide synthesis, andalso to regenerate glucose6P to maintain NADPHproduction by the oxidativephase.

The irreversible oxidative phaseGlucose-6-P is converted to ribulose-5-P with production of 2 molecules of NADPH and CO2 Three enzymatic reactions in the oxidative phase

G6PD is the committed step in the Pentose Phosphate Pathway because 6-Phosphoglucono-lactone has no other metabolic fate except to be converted to 6-phosphogluconate