蛋白编码基因中四倍简并位点碱基转换与颠换的规律研究

以同源性在７０％以上的６组同源蛋白为材料，从系统发生的角度研究发生在四倍简并位点上的转换和颠换的关系。考虑碱基组成对碱基替换的影响后，转换对颠换的优势在四倍简并位点也存在，但不如线粒体ＤＮＡ中显著。比较不同转换或颠换之间的关系发现，不同转换或颠换以十分接近的比率发生，Ａ－Ｇ转换与Ｃ－Ｔ转换的比率为０．９９：１，各种颠换相对于Ｔ－Ｃ转换的比率在０．６５－０．７３之间。进一步讨论了转换对颠换存在优势的原因，推测它可能与体内存在的诱变剂有关。

Study on the Principles of Base Change in 4- fold Degenerate Sites of Protein Coding Genes

The relationship of transition and transversion of base change in 4-fold degenerate sites of coding genes of 6 proteins, which showed 70% homology in wmposition investigated.Taking into account of the effects of base composition on base substitution, it was found that the transition-transversion bias was evident but not as pronounced as in mitochondrial DNA.Comparison of different kinds of transition or transversion indicated that they happened with rather equal vate, with 0.65- 0.73 for different kinds of transversion and 0.99 for A- G transition assuming that T- C transition was 1. The causes for transition- transversion bias is discussed and it is proposed that mutagens may play a role in it.