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甲基化造成的大量C→T转换,为进化提供了源源不断的突变,而同时其所编码的氨基酸则逐渐丧失了遗传上的保守性。与此相反,由G至A的原发性转换可能甚少,相应密码子所对应的氨基酸则相对稳定,从而使可避免甲基化的GDN和DGN三联密码成为保守氨基酸进化的必要条件。
A large number of C → T transitions caused by methylation provided a steady stream of mutations in evolution, while the amino acids encoded by them gradually lost their genetic conservation. In contrast, the primary conversion from G to A may be rare, and the amino acids corresponding to the corresponding codons are relatively stable, making the triple-Avoid GDN and DGN triplet codes necessary for the evolution of conserved amino acids.