Abstract

The human N-glycosylases SMUG1 and MBD4 catalyze the removal of uracil residues from DNA resulting from cytosine deamination or replication errors. For polymorphic variants of SMUG1 (G90C, P240H, N244S, N248Y) and the MBD4^cat catalytic domain (S470L, G507S, R512W, H557D), the structures of enzyme-substrate complexes were obtained by molecular dynamic simulation. It was experimentally found that the SNP variants of SMUG1, N244S and N248Y, had increased catalytic activity compared to the wild-type enzyme, probably due to the acceleration of the dissociation of the enzyme–product complex and an increase in the enzyme turnover rate. All other SNP variants of SMUG1 (G90C, P240H) and MBD4^cat, in which amino acid substitutions disrupted the substrate binding region and/or active site, had significantly lower catalytic activity than the wild-type enzymes.

中文翻译：

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人尿嘧啶-DNA-糖基化酶SMUG1和MBD4多态性变体活性的比较分析。

摘要

人N-糖基化酶SMUG1和MBD4催化从胞嘧啶脱氨或复制错误导致的DNA中去除尿嘧啶残基。对于SMUG1（G90C，P240H，N244S，N248Y）和MBD4 ^cat催化域（S470L，G507S，R512W，H557D）的多态变体，通过分子动力学模拟获得了酶-底物复合物的结构。通过实验发现，与野生型酶相比，SMUG1，N244S和N248Y的SNP变体具有增强的催化活性，这可能是由于酶-产物复合物解离的加快和酶转化率的提高。SMUG1（G90C，P240H）和MBD4^猫的所有其他SNP变体，其中的氨基酸取代破坏了底物结合区和/或活性位点，具有明显低于野生型酶的催化活性。