Question

Carboxypeptidase, which sequentially removes carboxy-terminal amino acid residues from its peptide substrates, is a single polypeptide of 307 amino acids. The two essential catalytic groups in the active site are furnished by Arg145 and Glu270.

(a) If the carboxypeptidase chain were a perfect α-helix, how far apart (in Å) would Arg145 and Glu270 be? Hint: See Fig 4-4a.

(b) Explain how the two amino acid residues can catalyze a reaction occurring in the space of a few angstroms.

Answer 1