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Subjects/Biochemistry/AIIMS 2018
AIIMS 2018
medium
flask-conical Biochemistry

Due to which of the following enzyme deficiency, vitamin C cannot be synthesised in humans?

A. L-Glucuronic acid oxidase
B. L-Gulonic acid reductase
C. L-Gulonolactone oxidase
D. L-Gulonolactone reductase

Explanation

L-Gulonolactone oxidase produces Vitamin C Uronic acid pathway, but only in plants & most animals. Humans cannot make vitamin C due to absence of L-Gulonolactone oxidase enzyme.(See fig) Uronic acid pathway- glucose is conveed to glucuronic acid, pentoses and, in some animals, to ascorbic acid (not in man). ADDITIONAL EDGE: Uronic Acid Pathway synthesize Glucuronic Acid, Pentoses and Vit C Uses of Glucuronic acid: Incorporated into proteoglycans (Glucuronate used) Acts as a conjugating agent (Phase II conjugation reactions like bilirubin conjugation)

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