Dodson M L, Lloyd R Stephen
The Sealy Center for Molecular Science and Department of Human Biological Chemistry and Genetics, The University of Texas Medical Branch, Galveston, TX , USA.
Free Radic Biol Med. 2002 Apr 15;32(8):678-82. doi: 10.1016/s0891-5849(02)00767-0.
The mechanisms by which various DNA glycosylases initiate the base excision repair pathways are discussed. Fundamental distinctions are made between "simple glycosylases," that do not form DNA single-strand breaks, and "glycosylases/abasic site lyases," that do form single-strand breaks. Several groupings of BER substrate sites are defined and some interactions between these groupings and glycosylase mechanisms discussed. Two characteristics are proposed to be common among all BER glycosylases: a nucleotide flipping step that serves to expose the scissile glycosyl bond to catalysis, and a glycosylase transition state characterized by substantial tetrahedral character at the base glycosyl atom.
本文讨论了各种DNA糖基化酶启动碱基切除修复途径的机制。区分了不形成DNA单链断裂的“简单糖基化酶”和形成单链断裂的“糖基化酶/无碱基位点裂解酶”。定义了碱基切除修复（BER）底物位点的几个分组，并讨论了这些分组与糖基化酶机制之间的一些相互作用。提出了所有BER糖基化酶共有的两个特征：一个用于将可裂解的糖基键暴露于催化作用的核苷酸翻转步骤，以及一个在碱基糖基原子处具有大量四面体特征的糖基化酶过渡态。
