Two alternative deprotecting procedures were employed for the synthesis of porcine vasoactive intestinal polypeptide (VIP). Besides HF, TFA-thioanisole was found to cleave all the protecting groups employed, Z, Bzl and Mts, suppressing a newly found side reaction, i.e., acid-catalyzed succinimide formation from Asp residues with the free carboxyl group. A small amount of the N-terminal His residue linked to Ser-Asp was found to be released on standing at pH 6.
猪血管活性肠肽(VIP)的合成采用了两种不同的脱保护程序。除了
氢氟酸外,发现TFA-
硫代
茴香醚能裂解所用的所有保护基团,包括苄酯、甲
砷酸和三甲基
硅基,并抑制了一种新发现的副反应,即自由羧基的
天冬氨酸残基在酸性催化下形成琥珀
酰亚胺。在pH 6下静置时,与Ser-Asp相连的N端组
氨酸残基有少量被释放。