General acid-base catalysis mediated by nucleobases in the hairpin ribozyme.
General acid-base catalysis mediated by nucleobases in the hairpin ribozyme.
复制标题
由发夹核酶中的核碱基介导的一般酸碱催化。
DOI：
10.1021/ja3067429
复制
发表时间：
2012-10-10
影响因子：
15
通讯作者：
Lilley DM
中科院分区：
文献类型：
--
作者：
Kath-Schorr S;Wilson TJ;Li NS;Lu J;Piccirilli JA;Lilley DM
The catalytic mechanism by which the hairpin ribozyme accelerates cleavage or ligation of the phosphodiester backbone of RNA has been incompletely understood. There is experimental evidence for an important role for an adenine (A38) and a guanine (G8), and it has been proposed that these act in general acid-base catalysis. In this work we show that a large reduction in cleavage rate on substitution of A38 by purine (A38P) can be reversed by replacement of the 5′-oxygen atom at the scissile phosphate by sulfur (5′-PS), which is a much better leaving group. This is consistent with A38 acting as the general acid in the unmodified ribozyme. The rate of cleavage of the 5′-PS substrate by the A38P ribozyme increases with pH log-linearly, indicative of a requirement for a deprotonated base with a relatively high pKa. On substitution of G8 by diaminopurine, the 5′-PS substrate cleavage rate at first increases with pH and then remains at a plateau, exhibiting an apparent pKa consistent with this nucleotide acting in general base catalysis. Alternative explanations for the pH dependence of hairpin ribozyme reactivity are discussed, from which we conclude that general acid-base catalysis by A38 and G8 is the simplest and most probable explanation consistent with all the experimental data.
登录
查看更多内容
影响因子：
4.5
作者：
Macelrevey, Celeste;Salter, Jason D.;Wedekind, Joseph E.
通讯作者：
Wedekind, Joseph E.
影响因子：
5.6
作者：
Kuzmin, YI;Da Costa, CP;Fedor, MJ
通讯作者：
Fedor, MJ
影响因子：
--
作者：
Nesbitt, S;Hegg, LA;Fedor, MJ
通讯作者：
Fedor, MJ
影响因子：
64.8
作者：
BUZAYAN, JM;GERLACH, WL;BRUENING, G
通讯作者：
BRUENING, G
影响因子：
4.8
作者：
Cottrell, Joseph W.;Scott, Lincoln G.;Fedor, Martha J.
通讯作者：
Fedor, Martha J.