Studies on Peptides. XCVII. Synthesis of Porcine Glu8-Vasoactive Intestinal Polypeptide (VIP)

The synthesis of Glu8-vasoactive intestinal polypeptide (porcine VIP) is described. A 1 M solution of trifluoromethanesulfonic acid-thioanisole (1 : 1 equiv.) in TFA was found to cleave all the protecting groups employed, Z, Z (OMe), Bzl and Mts, suppressing the acid-catalyzed aminosuccinimide formation of the Asp residue (position 3) with the free carboxyl group. The activity of Glu8-VIP was 1/7-1/8 of that of synthetic porcine VIP.