Glucagon is a peptide hormone produced by the pancreas that, with insulin, regulates blood glucose levels. Glucagon is comprised of 29 amino acid residues. Treatment with trypsin yields four fragments, while treatment with chymotrypsin yields six fragments. Identify the sequence of amino acid residues for glucagon, and determine whether any disulfide bridges are present.

Trypsin fragments

His-Ser-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Lys

Ala-Gln-Asp-Phe-Val-Gln-Trp-Leu-Met-Asn-Thr

Tyr-Leu-Asp-Ser-Arg

Arg

Chymotrypsin fragments

His-Ser-Gln-Gly-Thr-Phe

Thr-Ser-Asp-Tyr

Leu-Met-Asn-Thr

Ser-Lys-Tyr

Leu-Asp-Ser-Arg-Arg-Ala-Gln-Asp-Phe

Val-Gln-Trp.