A protein biochemist attempted to determine the amino acid sequence of a decapep

Question

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 nonapeptide. What is a possible sequence of the decapeptide? Use three-letter abbreviations in your answer, and add dashes between residues.

Explanation / Answer

No time to show working, the seq from N terminal to C terminal is :-

Met-Val-Lys-Tyr-Thr-Trp-Ala-Phe-Pro-Arg

Rule-

Trypsin cuts after Lys and Arg, but canot cut if it is succeeded by a proline (Imino acid)

Chymo cuts after aromatic amino acids like Tyr, Trp and Phe but again succeeding aa should not be proline

Cyanogen Bromide cuts after Methionine

CHEERS,

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