analogs containing substitution of Met31 by 3- and 4-(alkylthio)-substituted proline derivatives. To this end we have developed novel synthetic routes to enantiomerically pure N-Boc-4-cis- and -trans-(methylthio)prolines and racemic N-Boc-3-cis and -trans-[(4-methylbenzyl)thio]prolines. The protected mercaptoprolines were incorporated into Ac-CCK4 analogs using SPPS and were alkylated using various electrophiles
据报道,Boc-CCK4(Boc-Trp30-Met31-A
SP32-Phe33-NH2,CCK33编号)中的Met31残基被反式3-丙基-
L-脯氨酸取代产生了高效的选择性CCK-B激动剂。为了进一步探索CCK4受体结合构象中Met31侧链的结构要求,我们合成了几种Ac-CCK4类似物,其中包含被3-和4-(烷
硫基)-取代的脯
氨酸衍
生物取代的Met31。为此,我们开发了对映体纯的N-Boc-4-顺-和-反-(甲
硫基)脯
氨酸和外消旋的N-Boc-3-顺和-反-[(4-甲基苄基)
硫代]脯
氨酸的新颖合成途径。使用
SPPS将保护的巯基脯
氨酸掺入Ac-CCK4类似物中,并在从固体支持物上裂解后使用各种亲电试剂将其烷基化。结合测定表明,3-(烷
硫基)脯
氨酸类似物在CCK-B受体处的亲和力高于相应的4-(烷
硫基)脯
氨酸类似物,而反式-3-(烷
硫基)脯
氨酸的类似物具有更高的亲和力。 -(烷
硫基)脯
氨酸类似