关于核糖核酸酶的作用机制：咪唑和Zn2+催化二核苷酸裂解
On the mechanism of action of ribonucleases: dinucleotide cleavage catalyzed by imidazole and Zn2+.
作者信息
Breslow R, Huang D L, Anslyn E
机构信息
Department of Chemistry, Columbia University, New York, NY 10027.
出版信息
Proc Natl Acad Sci U S A. 1989 Mar;86(6):1746-50. doi: 10.1073/pnas.86.6.1746.
Cyclization/cleavage of the 2-(p-nitrophenyl) phosphate ester of propylene glycol is catalyzed by imidazole and, much more effectively, by Zn2+ with imidazole. In the latter case, the mechanism involves simultaneous Lewis acid/base catalysis. Similar Zn2+ and imidazole catalysis of cyclization/cleavage is seen with the dinucleotide 3',5'-UpU (uridylyluridine). Again, the zinc system is much more effective than is catalysis by imidazole alone, and in this case simultaneous Lewis acid/base catalysis substitutes for the sequential proton acid/base catalysis seen with polynucleotides or dinucleotides and imidazole buffer catalysts. A mechanism is proposed for catalysis of RNA cleavage by the enzyme ribonuclease A, and the relationship of that mechanism to the action of the enzyme model systems is discussed.
咪唑可催化丙二醇2-(对硝基苯基)磷酸酯的环化/裂解反应，而锌离子与咪唑共同作用时，催化效果更佳。在后一种情况下，反应机制涉及同时进行的路易斯酸/碱催化。对于二核苷酸3',5'-UpU（尿苷酰尿苷），也观察到了类似的锌离子和咪唑催化的环化/裂解反应。同样，锌离子体系比单独使用咪唑的催化效果要好得多，在这种情况下，同时进行的路易斯酸/碱催化替代了多核苷酸或二核苷酸与咪唑缓冲催化剂所发生的顺序质子酸/碱催化。本文提出了一种核糖核酸酶A催化RNA裂解的机制，并讨论了该机制与酶模型系统作用之间的关系。
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