Salemme F R, Miller M D, Jordan S R
Proc Natl Acad Sci U S A. 1977 Jul;74(7):2820-4. doi: 10.1073/pnas.74.7.2820.
Several recent protein crystallographic structure determinations have demonstrated the existence of considerable tertiary structural similarity among proteins otherwise having little similarity in either amino acid sequence or biological function. In order to assess the possibility that such proteins may have arisen through processes of divergent evolution from a common ancestor, a graphical presentation is given which correlates the pattern of allowed single base substitutions defined by the genetic code with the associated changes in the structural properties of the encoded amino acids. The results show that while a large degree of structural conservation is evident due to codon synonomy, there is, in general, little tendency for the code to be structurally conservative in the majority of the cases where codon single-base changes result in amino acid substitutions. The possible consequences of this pattern of potential amino acid substitutions are discussed in relation to protein evolutionary processes.
最近的几项蛋白质晶体学结构测定表明，在氨基酸序列或生物学功能上几乎没有相似性的蛋白质之间，存在着相当大的三级结构相似性。为了评估这些蛋白质可能是通过从共同祖先的趋异进化过程产生的可能性，给出了一种图形表示，它将遗传密码定义的允许单碱基替换模式与编码氨基酸结构特性的相关变化联系起来。结果表明，虽然由于密码子同义性，很大程度的结构保守性是明显的，但一般来说，在密码子单碱基变化导致氨基酸替换的大多数情况下，密码子在结构上几乎没有保守的趋势。结合蛋白质进化过程讨论了这种潜在氨基酸替换模式的可能后果。
