An unsulfated form of human cholecystokinin (hCCK-33) was synthesized by successive azide condensations of seven peptide fragments, followed by deprotection with 1 M trimethylsilyl trifluoromethanesulfonate/trifluoroacetic acid. The phenolic group of Tyr (position 27) was selectively sulfated with pyridine-SO3 complex, after reversible masking of other functional groups with hard base (F-)-labile protecting groups, i.e., the amino functions with 9-fluorenyl-methyloxycarbonyl group and the hydroxyl functions of 4 Ser residues with tert-butyldiphenylsilyl groups. In terms of pancreatic protein output and capillary blood flow in dogs, the relative potency of synthetic hCCK-33 with respect to that of synthetic CCK-8 (taken as 1 on a molar basis) was 0.9. In terms of gastric acid and pepsin output in rat in vivo assays, synthetic hCCK-33 was about 2- to 3-fold more potent than CCK-8 on a molar basis.
一种人胆囊收缩素(hCCK-33)的非
硫酸化形式通过七个肽片段的连续
叠氮化缩合合成,随后用1 M三甲基
硅烷三氟甲磺酸盐/
三氟乙酸去保护。Tyr(位置27)的
酚羟基在用具有硬碱性(F-)的保护基团可逆掩蔽其他功能基团后,选择性地与
吡啶-SO3复合物进行
硫酸化,即用9-
氟烯基-甲氧基羧基基团保护
氨基功能,以及用叔丁基二苯基
硅基团保护4个
丝氨酸残基的羟基功能。在犬的胰腺蛋白输出和毛细血管血流方面,合成的hCCK-33相对于合成的CCK-8(以1为摩尔基准)的相对效力为0.9。在大鼠体内实验中,合成的hCCK-33在胃酸和胃
蛋白酶的输出方面,其效力比CCK-8高约2到3倍。