Determining the Primary Structure of a Peptide

Amino acid analysis of a dodecapeptide X produced the following mixture: 4Ala, 2Gln, 2Met, 2Phe & 2Ser.
N-Terminal analysis identified the sequence: Ser-Ala-Gln---. C-Terminal analysis identified: ---Ala-Phe. Selective peptide cleavage gave the following results.

Cyanogen bromide treatment generates three fragments:
      A dipeptide, Ala-Phe.
      A tetrapeptide (A) having a homoserine (Hsr) at the C-terminus.
      A hexapeptide (B) having a homoserine (Hsr) at the C-terminus.

Chymotrypsin gave a single hexapeptide (C) and no other products.

Select an amino acid notation:   Three letter abbreviation
    One letter abbreviation

Using the notation selected above, write an amino acid sequence for each of the unknown peptides in the designated answer box. You may run the letter abbreviations together, or separate them by spaces or dashes.

A ....   Use Hsr or Z as a symbol for homoserine.

B ....   Use Hsr or Z as a symbol for homoserine.

C ....

D ....

   



This script written by William Reusch, Dept. of Chemistry, Michigan State University. Please send comments and corrections to whreusch@pilot.msu.edu.