Vitamin C / ascorbic acid: Sources, Daily requirement, Functions, and Deficiency || Usmle

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Vitamin C / ascorbic acid: Sources, Daily requirement, Functions, and Deficiency manifestations

Ascorbate. Water-soluble, cofactor for enzymatic reactions
• Anti-oxidant properties, guards against oxidative stress
• Vit C serves as a cofactor for prolyl-4-hydroxylase and lysyl hydroxylase, an enzyme involved in collagen synthesis.
• Stable collagen cannot form without proline and lysine hydroxylation. This hydroxylation takes place in the ER.
• Hydroxylation of proline secures the collagen chains in triple-helix formation.
• The subsequent hydroxylation of lysine is required for cross-linking.
• Deficiency of lysyl hydroxylase: Ehlers-Danlos Syndrome Type 6
Other roles:
Cofactor for dopamine hydroxylase (dopamine → norepinephrine)
Required for reduction of iron from Fe3+ → Fe2+, allowing absorption in the duodenum.
Deficiency → scurvy.