A series of studies were originally conducted on two peptide chains linked by one or more disulfide bridges, and it was found that the N-terminal of the peptides are Valine and Proline.

-Disulfide bridges were broken by performic acid, two cysteic acid (Cys.SO3H) residues were formed from each cystine residue initially present.

-Then, the following five parts were obtained in hydrolysis with trypsin.

Val-Ser-Lys-Cys.SO3H-Leu Gly-Cys.SO3H-Phe-Ile-Ala

Pro-Arg Glu-Trp-Cys. SO3H-Gly

Cys. SO3H-Leu-Tyr-Cys. SO3H-Arg

- Five parts were obtained by hydrolysis of the original peptide with pepsin, then treatment with performic acid.

Val-Ser-Lys-Cys.SO3H-Leu Ile-Ala

Pro-Arg-Gly-Cys.SO3H-Phe Trp- Cys.SO3H-Gly

Ty Cys.SO3H-Arg-Glu

- Part of the original sample was hydrolyzed with pepsin without treatment with performic acid and the formed parts were separated. One of these pieces was further divided with performic acid and gave the following pieces.

Val-Ser-Lys- Cys.SO3H-Leu

Trp- Cys.SO3H-Gly



What can be achieved from these results about primary structure?