这个词是什么意思？
Systems consisting of two enzymes, a modification methylase and a restriction endonuclease. They are closely related in their specificity and protect the DNA of a given bacterial species. The methylase adds methyl groups to adenine or cytosine residues in the same target sequence that constitutes the restriction enzyme binding site. The methylation renders the target site resistant to restriction, thereby protecting DNA against cleavage.
中文名称索引；定义为 MeSH 英文原文，尚未逐条译审。MESH:D015280 · MeSH 2026。
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