DNA Guanine Base Methylation by Alkylation

DNA guanine base methylation by alkylation refers to the covalent addition of a methyl group to specific positions on the guanine base within DNA, primarily as a result of exposure to alkylating agents. This process is a form of DNA damage that can have significant biological consequences, including mutagenesis and cytotoxicity. The most common sites for methylation on guanine are N7-guaninie (N7-MeG), and O6-guaninie (O6-MeG). O6-methylguanine mispairs with thymine during replication, resulting in point mutations that contribute significantly to carcinogenesis if not repaired. The primary repair mechanism for O6-MeG lesions involves the enzyme O6-methylguanine-DNA methyltransferase (MGMT, also known as AGT).

DNA alkylation leading to base methylation