Solid-phase synthesis of porcine vasoactive intestinal peptide.

The 28-residue sequence of porcine vasoactive peptide (VIP) was assembled on a benzhydrylamine resin support, cleaved by HF treatment, and purified by ion-exchange and partition chromatography. In addition to the normal criteria, the homogeneity of the final material, obtained in 16% yield, was assessed by reverse-phase high performance liquid chromatography and the isolation and examination of cyanogen bromide cleavage fragments by the same technique. The purified VIP possessed characteristic inhibitory effects on pentagastrin-induced gastric acid release in the dog. Upon storage, even as the lyophilized powder in vacuo, HPLC revealed the slow formation of a contaminant possibly representing deamidated peptide.