Treatment of a polypeptide with 2-mercaptoethanol yields two polypeptides:
1. Ala-Val-Cys-Arg-Thr-Gly-Cys-Lys-Asn-Phe-Leu
2. Tyr-Lys-Cys-Phe-Arg-His-Thr-Lys-Cys-Ser
Treatment of the intact polypeptide with trypsin yields fragments with the following amino acid compositions:
3. (Ala, Arg, Cys2, Ser, Val)
4. (Arg, Cys2, Gly, Lys, Thr, Phe)
5. (Asn, Leu, Phe)
6. (His, Lys, Thr)
7. (Lys, Tyr)
Indicate the positions of the disulfide bonds in the intact polypeptide.