Question

Collagen synthesized in the presence of radioactively labeled proline (C14 labeling) has radioactive residues incorporated into its sequence. However, collagen synthesized in the presence of radioactively labeled hydroxyproline (C14 labeling) does not become radiolabeled. Why?

Answer 1

Ans:-

concept:- the main catch point is that que is that the hydroxyproline which is present in collagen is formed only by hydrolixation of proline which is already present in the polypeptide chain. No hydroxyproline is taken from out side media during collagen synthesis.

so when we give radiolable proline it get incorporated initially in the polypeptide chain . Then this radiolable proline is hydroxylated to form radiolable hydroxyproline which further form radiolable collagen.

But if we will give radiolable hydroxyproline then it will not be incorporated in polyptide chain and hence collagen which is formed will not be radiolabled.