1) The oxidative phase generates NADPH
The oxidative branch of the pathway generates NADPH and pentose-5-phosphate, through the following reactions:
a) Glucose-6-phosphate is dehydrogenated to 6-phosphogluconate via 6- phosphoglucano-lactone by glucose-6-phosphate dehydrogenase in presence of NADP' and the cofactors Mg++, Mn++ or Ca++. Glucose-6-phosphate dehydrogenase deficiency is an inherited disease characterized by haemolytic anaemia if the patient is treated with an oxidant drug (such as primaquine and sulphonamide) or ingests fava beans.
b) 6-phosphogluconate is oxidized by 6-phosphogluconate dehydrogenase in the presence of coenzyme NADP+ and cofactors Mg++, Mn++ or Ca++ to 3-keto 6 phosphogluconate which is decarboxylated to form ribulose-5 phosphate.