Molecular Mechanisms of Human DNA Polymerase B Catalysis, Fidelity and Selective

DNA聚合酶的碱基选择和催化机制探索使用dNTP类似物的工具包，有双膦酸盐代替B， y桥氧。这些类似物是Pol B底物，其离开基团具有广泛的分散性电子性质，pKa4值范围从7.8到12.3，使我们能够使用预稳态动力学测量来确定化学过渡态发生的脱氧核苷酸的正确和错误选择。工具箱中特别重要的成员包括所有四种单独合成的(R)-和(S)-B，Y-CHF和B，Y-CHCI非对映体。我们最近观察到Pol B中(R)-CHF的明显立体选择涉及F与Arg183的静电相互作用，这是Pol B等X族Pol所特有的，是a的动力

DNA polymerase mechanisms of base selection and catalysis are explored using a tool-kit of dNTP analogs that have bisphosphonates in place of the B,Y-bridge oxygen. These analogs are Pol B substrates that have leaving groups with widely dispirate electronic properties, pKa4 values ranging from 7.8 to 12.3, enabling us to use presteady state kinetic measurements to determine the selection of right and wrong deoxynucleotides occurring at the chemical transition state. Especially important members of the toolkit include all four individually synthesized (R)- and (S)-B,Y-CHF and B,Y-CHCI diastereomers. Our recent observation of a pronounced stereoselection for (R)-CHF in Pol B involving an electrostatic interaction of F with Arg183, unique to family X pols such as Pol B, serves as the impetus for a