EC number 1.2.1.9 IntEnz IntEnz view ExPASy NiceZyme view | CAS number 9028-92-6 BRENDA BRENDA entry KEGG KEGG entry | |
Glyceraldehyde-3-phosphate dehydrogenase (NADP+) (EC 1.2.1.9) (GAPN) is an enzyme that irreversibly catalyzes the oxidation of glyceraldehyde-3-phosphate (GAP) to 3-phosphoglycerate (3-PG or 3-PGA) using the reduction of NADP+ to NADPH. GAPN is used in a variant of glycolysis that conserves energy as NADPH rather than as ATP. The NADPH and 3-PG can then be used for synthesis. The most familiar variant of glycolysis uses glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoglycerate kinase to produce ATP. GAPDH is phosphorylating. GAPN is non-phosphorylating.
GAPN was reported first by Rosenberg and Arnon in 1954. It has been found in plants, algae, and bacteria.
Reactions
Glyceraldehyde-3-phosphate dehydrogenase (NADP+) catalyzes
GAP + NADP+ + H2O → 3-PG + NADPH + H+Glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase catalyze
GAP + NAD+ + Pi ⇌ 1,3-bisphosphoglycerate + NADH + H+ 1,3-bisphosphoglycerate + ADP ⇌ 3-PG + ATPUsually [NADPH] / [NADP+] >> 1 >> [NADH] / [NAD+].