Glyceraldehyde-3-phosphate dehydrogenase (NADP+) (phosphorylating)

Glyceraldehyde-3-phosphate dehydrogenase (NADP+) (phosphorylating), also sometimes referred to as glyceraldehyde-3-phosphate dehydrogenase (NADP+ dependent), is an enzyme that catalyzes the reversible oxidative phosphorylation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate, utilizing NADP+ as a cofactor and inorganic phosphate. This reaction is a crucial step in certain metabolic pathways, including specific types of glycolysis found in some organisms and in various biosynthetic pathways.

Unlike the more common glyceraldehyde-3-phosphate dehydrogenase (GAPDH) that utilizes NAD+, this enzyme uses NADP+ as the electron acceptor. This cofactor preference is important because NADP+ generally plays a more significant role in anabolic, reductive biosynthetic pathways, as opposed to the catabolic, energy-generating role of NAD+.

The enzyme's systematic name is glyceraldehyde-3-phosphate:NADP+ oxidoreductase (phosphorylating). Its activity involves the oxidation of the aldehyde group of glyceraldehyde-3-phosphate, the reduction of NADP+ to NADPH, and the incorporation of inorganic phosphate to form 1,3-bisphosphoglycerate. This product can then be used in subsequent steps of biosynthesis or energy metabolism, depending on the organism and pathway.

The phosphorylating activity distinguishes this specific enzyme from other glyceraldehyde-3-phosphate dehydrogenases that might not directly incorporate inorganic phosphate into the product. The presence and function of this enzyme are often highly dependent on the specific metabolic needs and enzymatic repertoire of the organism in question. The regulation of this enzyme's activity can be influenced by factors such as substrate availability, NADP+/NADPH ratios, and other cellular signals, contributing to the control of carbon flux through the pathways in which it participates.