Determine the sequence of amino acids of an octapeptide usin

Determine the sequence of amino acids of an octapeptide using the following information: Treatment of the peptide with the Edman reagent resulted on the phenylthiohydantoin derivative of Phe. Cleavage of the peptide with chymotrypsin produced free among other fragments a dipeptide Arg-Pro and a pentapeptide Gly-Ser-Lys-Ile-Trp. Treatment of the peptide with carboxypeptidases A or B did not produce any free amino acids.

Solution

The sequence of the octapeptide was :

N-Term\'l Phe-Gly-Ser-Lys-Ile-Trp-Arg-Pro C-Trm\'l