A protein biochemist attempted to determine the amino acid sequence of a decapeptide. Use the results from the trypsin, chymotrypsin, and cyanogen bromide treatments to suggest the amino acid sequence of this decapeptide. Trypsin digestion gave two fragments, containing the following residues (not in order): T1: Ala, Arg, Phe, Pro, Thr, Trp, Tyr T2: Lys, Met, Val Chymotrypsin digestion gave three fragments with the following residues (not in order): CT1: Ala, Arg, Phe, Pro CT2: Thr, Trp CT3: Lys, Met, Tyr, Val N-terminal analysis of the CT1 tetrapeptide indicated that the N-terminal amino acid was Ala. The cyanogen bromide gave only one single amino acid, methionine, and a nanopeptide.

I know that Trypsin cleaves after Lys and Arg, but not on the N-side of Pro. Chymotrypsin cleaves after Phe, Trp, and Tyr, but not on the N-side of Pro. Cyanogen bromide cleaves after Met. My professor also told me that it begins with Met, & ends with Lys.