二(2-苯并咪唑亚甲基)胺合锰(Ⅱ)配合物水解切割DNA

Hydrolytic Cleavage of DNA by a Mn(Ⅱ) Complex with Bis(2-benzimidazolylmethyl)amine

本文合成并表征了二(2鄄苯并咪唑亚甲基)胺合锰髤配合物。我们利用凝胶电泳实验研究,发现该配合物在近生理条件下,能有效地切割双链pBR322DNA。通过采用在反应体系中加入自由基清除剂,无氧操作实验,脱水丙二醛产物分析,以及T4DNA连接酶连接实验等方法,确认该切割反应是通过水解途径进行的。进一步地,我们对切割反应进行了较详细的动力学研究,求出其催化速率常数Kcat为0.72±0.02h-1(pH=8,37℃)。

MnL(here, L=bis(2-benzimidazolylmethyl)amine) was synthesized and characterized. The Mn( complex acts as an artificial nuclease by effectively promoting the hydrolysis of plasmid DNA at physiological pH and temperature. The studies on mechanism of DNA cleavage by added radical scavengers, rigorously anaerobic experiments, analysis for malondialdehyde-like products, and the religation assays show that DNA cleavage mediated by MnL occurs via a hydrolytic path. Values for apparent rate constants for the decrease of supercoiled DNA (form Ⅰ) and the increase of linearized DNA (form Ⅲ) were obtained under different complex concentrations at physiological pH and temperature. The catalytic rate constant (Kcat) was obtained on the transformation of the Michaelis-Menten equation from a best-fit line of the apparent rate constant versus complex concentration. The estimation of Kcat for the decrease of form Ⅰ shows a rate enhancement factor of 108.