The isolation and sequencing of human gastric inhibitory peptide (GIP)

Abstract

Human GIP 1–42 and fragments of human GIP corresponding to GIP 10–42, GIP 11–42, and GIP 17–42 were isolated from acid-ethanol extracts of human small intestines with the aid of an anti-GIP serum specific for the extreme C-terminal portion of the GIP molecule. The full sequence of human GIP has been established by Edman degradation of these peptides and fragments thereof by automatic gas-phase sequencing. Human GIP differs from porcine GIP at residues 18 and 34. The sequence of human GIP is thus: Tyr-Ala-Glu-Gly-Thr-Phe-Ile-Ser-Asp-Tyr-Ser-Ile-Ala-Met-Asp-Lys-Ile-His-Gln-Gln-Asp-Phe-5 10 15 20 Val-Asn-Trp-Leu-Leu-Ala-Glu-Lys-Gly-Lys-Lys-Asn-Asp-Trp,Lys-His-Asn-Ile-Thr-Gln. Amino acid 25 30 35 40 residues 18 and 34 are Arg and Ser, respectively, in porcine GIP.