Question
Which of the following enzymes is dependent on Vitamin C for its activity?
| A. | Lysyl Dehydrogenase |
| B. | Lysyl Oxidase |
| C. |
Prolyl Hydroxylase |
| D. |
Hydroxyprolyl Kinase |
|
Correct Answer � C Explanation |
 |
Prolyl Hydroxylase
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Prolyl hydroxylase is a key enzyme involved in collagen synthesis.
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It hydroxylates proline residues in procollagen, an essential step that stabilizes the collagen triple helix via hydrogen bonding.
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This enzyme requires Vitamin C (ascorbic acid) as a cofactor to maintain its iron in the ferrous (Fe²⁺) state during the hydroxylation reaction.
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Vitamin C deficiency (as in scurvy) leads to defective collagen formation, resulting in symptoms like bleeding gums, poor wound healing, and fragile capillaries.
Why Other Options Are Incorrect:
A. Lysyl Dehydrogenase
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Not a recognized enzyme in collagen biosynthesis or Vitamin C metabolism. Possibly a distractor or misnomer.
B. Lysyl Oxidase
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Involved in cross-linking of collagen and elastin fibers in the extracellular matrix.
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Requires copper as a cofactor, not Vitamin C.
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Deficiency causes connective tissue disorders (e.g., Menkes disease), but not related to ascorbic acid.
D. Hydroxyprolyl Kinase
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Not a standard enzyme in collagen or connective tissue metabolism.
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Likely a distractor with no established physiological role or vitamin dependency.