Hydroxylation of proline requires -

Ans. is 'c' i.e., Vitamin C o Hydroxylation of proline and lysine residue takes place during post-translational modification in rough ER. The enzyme catalyzing the reactions are prolyl hydroxylase (for proline) and lysyl hydroxylase (for lysine). Both these enzymes are dioxygenases using molecular oxygen (O2) and cofactor for both these enzymes is vitamin C (ascorbic acid). a-Ketoglutatrate is a coreductant, which is oxidized to succinate.Proline (or lysine) + a-ketoglutarate + O2Prolyl (or lysyl) hydroxylase-----------------------Vitamin 'C'Hydroxyproline (or hydroxylysine)+Succinateo These hydroxylated amino acids are not reprsented in the genetic code (i.e. there is no t-RNA for these), therefore they have to be synthesized post-translationally from proline and lysine residue in the polypeptides.