Thio Effects on the Departure of the 3′-Linked Ribonucleoside from Diribonucleoside 3′,3′-Phosphorodithioate Diesters and Triribonucleoside 3′,3′,5′-Phosphoromonothioate Triesters: Implications for Ribozyme Catalysis
作者:Tuomas Lönnberg、Mikko Ora、Sami Virtanen、Harri Lönnberg
DOI:10.1002/chem.200601835
日期:2007.5.25
mixture of 3',3'- and 3',5'-diesters, and isomerized to 2',3',5'- and 2',2',5'-triesters. With phosphorodithioate diesters 2 a,b, hydroxide-ion-catalyzed cleavage of the P--O3' bond is the only reaction detected at pH >6, but under more acidic conditions desulfurization starts to compete with the cleavage. The 3',3'-diesters do not undergo isomerization. The hydroxide-ion-catalyzed cleavage reaction
为机械解释大核酶的硫效应提供坚实的化学基础,已研究了三核糖核苷3',3',5'-单硫代磷酸三酯和二核糖核苷3',3'-二硫代磷酸二酯的裂解。为阐明离去的3'-连接核苷的相邻羟基的作用,水解2',3'-O-亚甲基腺苷-5'-基双[5'-O-甲基尿素-3'-基]磷酸一硫代磷酸酯(将1a)与水解2',3'-O-亚甲基腺苷-5'-基5'-O-甲基尿素-3'-基2',5'-二-O-甲基尿素-3'-进行了比较磷酸一硫代磷酸酯(1 b)和双[uridin-3'-yl]二硫代磷酸酯(2 a)水解为uridin-3'-yl 2',5'-di-O-methyluridin-3'的水解 二硫代磷酸正酯(2 b)。在宽pH范围内通过RP HPLC跟踪反应。单硫代磷酸酯三酯1a,b经历两个竞争反应:将起始原料裂解为3',3'-和3',5'-二酯的混合物,并异构化为2',3',5'-和2 ',2',5'-三酸酯。对于二硫代磷酸二酯2a,b,在pH>