glucuronolactone reductase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: L-gulono-1,4-lactone + NADP+ = D-glucurono-3,6-lactone + H+ + NADPH. [EC:1.1.1.20, RHEA:18925]

Glucuronolactone reductase activity catalyzes the reduction of D-glucuronolactone to L-gulono-1,4-lactone. This enzymatic activity is crucial for the biosynthesis of L-ascorbic acid (vitamin C) in some organisms. The enzyme utilizes NADPH as a reducing agent and requires a specific cofactor, such as a metal ion, for its activity.
Glucuronolactone reductase is a key enzyme in the L-ascorbic acid biosynthetic pathway. It acts on the penultimate step, converting D-glucuronolactone, which is derived from D-glucose, to L-gulono-1,4-lactone. This reaction involves the transfer of electrons from NADPH to the substrate, resulting in the reduction of the carbonyl group of D-glucuronolactone to a hydroxyl group, forming L-gulono-1,4-lactone.
L-gulono-1,4-lactone is then readily converted to L-ascorbic acid by a subsequent enzyme, L-gulono-γ-lactone oxidase.
The molecular function of glucuronolactone reductase activity is essential for vitamin C biosynthesis in organisms that lack the ability to obtain vitamin C from their diet. This includes several species of animals, including humans and primates.
In humans, the gene for glucuronolactone reductase is non-functional, leading to the inability to synthesize vitamin C. Therefore, humans must obtain vitamin C from dietary sources.'
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Proteins (2)

Compounds (12)