This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Which of the following enzymes require Vitamin C for their activity? 
Select and explain. 
A. Procollagen proline hydroxylase, B. Procollagen amino peptidase, C. Procollagen carboxyl peptidase, D. Lysyl oxidase
A: Procollagen proline hydroxylase
Answer: A: Procollagen proline hydroxylase 
Explanation: Vitamin C plays the role of a coenzyme in hydroxylation of proline and lysine while protocollagen is converted to collagen  (i.e.  post-translational modification). The hydroxylation reaction is catalysed by lysyl hydroxylase  (for  lysine)  and prolyl  hydroxylase (for  proline).