科研之友
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摘要
DNA glycosylase AlkD excises N7-methylguanine (7mG) by a unique but unknown mechanism, in which the damaged nucleotide is positioned away from the protein and the phosphate backbone is distorted. Here, we show by methylphosphonate substitution that a phosphate proximal to the lesion has a significant effect on the rate enhancement of 7mG depurination by the enzyme. Thus, instead of a conventional mechanism whereby protein side chains participate in N-glycosidic bond cleavage, AlkD remodels the DNA into an active site composed exclusively of DNA functional groups that provide the necessary chemistry to catalyze depurination.
- 出版日期2013-10-22
