Chapter 21, Problem 66P

Treatment of a polypeptide with 2-mercaptoethanol yields two polypeptides with the following primary structures:

Val-Met-Tyr-Ala-Cys-Ser-Phe-Ala-Glu-Ser

Ser-Cys-Phe-Lys-Cys-Trp-Lys-Tyr-Cys-Phe-Arg-Cys-Ser

Treatment of the original intact polypeptide with chymotrypsin yields the following peptides:

1. Ala, Glu, Ser

2. 2 Phe, 2 Cys, Ser

3. Tyr, Val, Met

4. Arg, Ser, Cys

5. Ser, Phe, 2 Cys, Lys, Ala, Trp

6. Tyr, Lys

Determine the positions of the disulfide bridges in the original polypeptide.