Transesterification of a phosphodiester bond of RNA models has been studied in various buffer solutions, under neutral and slightly alkaline conditions in H2O and D2O. The results show that imidazole is the only buffer system where a clear buffer catalysis on the cleavage of a phosphodiester bond is observed. The rate enhancement in sulphonic acid buffers is smaller, and a sulphonate base, particularly
在中性和弱碱性条件下,在H 2 O和D 2中,已在各种缓冲溶液中研究了RNA模型的
磷酸二酯键的酯交换反应O.结果表明,
咪唑是唯一的缓冲体系,在该体系中观察到了对
磷酸二酯键断裂的清晰的缓冲催化作用。
磺酸缓冲液中的速率提高较小,特别是
磺酸碱作为催化剂没有活性。然而,
咪唑的增速作用是催化的,
磺酸盐缓冲液的催化失活可归因于它们的结构和/或电荷。
咪唑催化是一个复杂的系统,除了一级反应外,还涉及一个对
咪唑浓度具有二级依赖性的过程。随着酸性
咪唑缓冲液(pH