Glyceraldehyde-3-phosphate dehydrogenase (NADP+)

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.^[1] It has been found in plants, algae, and bacteria.^[2]

Reactions

Glyceraldehyde-3-phosphate dehydrogenase (NADP+) catalyzes

GAP + NADP⁺ + H₂O → 3-PG + NADPH + H⁺

GAP + NAD⁺ + P_i ⇌ 1,3-bisphosphoglycerate + NADH + H⁺

1,3-bisphosphoglycerate + ADP ⇌ 3-PG + ATP

Usually [NADPH] / [NADP⁺] >> 1 >> [NADH] / [NAD⁺].

↑ Rosenberg LL, Arnon DI (1955). "The preparation and properties of a new glyceraldehyde-3-phosphate dehydrogenase from photosynthetic tissues". J. Biol. Chem. 217 (1): 361–71. PMID 13271400.
↑ Boyd DA, Cvitkovitch DG, Hamilton IR (1995). "Sequence, expression, and function of the gene for the nonphosphorylating, NADP-dependent glyceraldehyde-3-phosphate dehydrogenase of Streptococcus mutans". J. Bacteriol. 177 (10): 2622–7. PMC 176930. PMID 7751269.

Aldehyde/oxo oxidoreductases (EC 1.2)

1.2.1: NAD or NADP	Aldehyde dehydrogenase Acetaldehyde dehydrogenase Long-chain-aldehyde dehydrogenase

1.2.2: cytochrome	Formate dehydrogenase (cytochrome)

1.2.3: oxygen	Aldehyde oxidase

1.2.4: disulfide	Oxoglutarate dehydrogenase complex Pyruvate dehydrogenase Branched-chain alpha-keto acid dehydrogenase complex BCKDHA BCKDHB DBT DLD

1.2.7: iron-sulfur protein	Pyruvate synthase

Enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list)

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