Glycerol-3-phosphate 1-dehydrogenase (NADP+)
Glycerol-3-phosphate 1-dehydrogenase (NADP+), also known as glycerol-3-phosphate dehydrogenase [NAD(P)+] and GPDH(NADP+), is an oxidoreductase enzyme (EC 1.1.1.178). It catalyzes the reversible reaction between glycerol-3-phosphate and glycerone phosphate, using NADP+ as a cofactor. This enzyme plays a role in glycerol metabolism, glycerophospholipid metabolism, and the glycerol shuttle.
Function
This enzyme facilitates the interconversion of dihydroxyacetone phosphate (DHAP) and glycerol-3-phosphate, utilizing NADP+ and NADPH as the oxidizing and reducing agents, respectively. The reaction is as follows:
glycerol 3-phosphate + NADP+ ⇌ dihydroxyacetone phosphate + NADPH + H+
The primary function of Glycerol-3-phosphate 1-dehydrogenase (NADP+) is to participate in metabolic pathways involving glycerol. It can contribute to both the production and consumption of glycerol-3-phosphate, depending on the cellular needs.
Role in Metabolism
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Glycerol Metabolism: The enzyme plays a direct role in the metabolism of glycerol, converting it to DHAP or vice versa.
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Glycerophospholipid Metabolism: G3P is a precursor for the synthesis of glycerophospholipids, major components of cell membranes. This enzyme, therefore, indirectly affects membrane synthesis.
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Glycerol Shuttle: Like other glycerol-3-phosphate dehydrogenases (e.g., the mitochondrial version that uses FAD), it can function as part of a glycerol shuttle mechanism for transporting reducing equivalents into or out of cellular compartments.
Enzyme Classification
Glycerol-3-phosphate 1-dehydrogenase (NADP+) belongs to the oxidoreductase class of enzymes, specifically those acting on the CH-OH group of donors with NAD+ or NADP+ as acceptor. Its systematic name is sn-glycerol-3-phosphate:NADP+ 1-oxidoreductase.
Isozymes
It should be noted that other glycerol-3-phosphate dehydrogenases exist, including those that utilize NAD+ (EC 1.1.1.8) and FAD. These isozymes may have different subcellular localization and play distinct roles in cellular metabolism. The key differentiating factor for this specific enzyme is its use of NADP+ as a cofactor.