NADPH+, H+ is generated in the reaction catalysed by

Step 1 of HMP Pathway Glucose-6-phosphate is oxidized by NADP+ dependent Glucose-6-phosphate dehydrogenase (GPD). 6-phospho gluconolactone is formed. One molecule of NADPH is formed in the reaction (Fig. 10.1). This is the rate-limiting step. Regulation is affected by this enzyme.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th Edition, Page no: 113