Case Study#2

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Discussion

• Ascorbic acid serves as a common reductant/cofactor in many enzymatic reactions (especially those requiring reduced Fe2+).
  1) Carnitine Synthesis
  2) Catecholamine Synthesis
  3) Peptide Hormone Synthesis
  4) Tyrosine Metabolism
  5) Generic Antioxidant
  6) Role in Immune Function?

• The critical functional role is to serve as a cofactor for protocollagen hydroxylase, the enzyme responsible for hydroxylation of the prolyl and lysyl residues in collagen.

• The triple-helix structure of mature collagen is markedly stabilized by hydroxylation (Tm of 24 ºC vs. 58 ºC) as it allows the formation of a water-mediated hydrogen bond between collagen strands.

• By an independent mechanism, the synthesis of proteoglycans and protocollagen is decreased in ascorbic acid deficiency (inhibition of insulin-like growth factor I?).