Doi Yusuke, Hitomi Kenichi, Tainer John A, Iwai Shigenori
Division of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Nucleic Acids Symp Ser (Oxf). 2005(49):195-6. doi: 10.1093/nass/49.1.195.
Endonuclease III is a base excision repair enzyme that recognizes oxidized pyrimidine bases including thymine glycol. This enzyme is a glycosylase/AP-lyase and forms a Schiff base-type intermediate with the substrate after the damaged base is removed. To investigate its substrate recognition mechanism by X-ray crystallography, we synthesized oligonucleotides containing 2'-fluorothymidine glycol (1-(2-deoxy-2-fluoro-beta-D-ribofuranosyl)-5,6-dihydro-5,6-dihydroxythymine), expecting that the electron-withdrawing fluorine atom at the 2' position would stabilize the covalent intermediate. Complex formation of the substrate analogs containing each thymine glycol isomer with endonuclease III was analyzed.
核酸内切酶III是一种碱基切除修复酶，可识别包括胸腺嘧啶乙二醇在内的氧化嘧啶碱基。该酶是一种糖基化酶/脱嘌呤嘧啶核酸裂合酶，在去除受损碱基后与底物形成席夫碱型中间体。为了通过X射线晶体学研究其底物识别机制，我们合成了含有2'-氟胸腺嘧啶乙二醇（1-(2-脱氧-2-氟-β-D-呋喃核糖基)-5,6-二氢-5,6-二羟基胸腺嘧啶）的寡核苷酸，期望2'位的吸电子氟原子能够稳定共价中间体。分析了含有每种胸腺嘧啶乙二醇异构体的底物类似物与核酸内切酶III的复合物形成情况。
