Kimura M
Proc Natl Acad Sci U S A. 1969 Aug;63(4):1181-8. doi: 10.1073/pnas.63.4.1181.
The rate of amino acid substitutions in the evolution of homologous proteins is remarkably constant. Furthermore, estimated rates of amino acid substitutions based on comparisons of the alpha hemoglobin chains of various mammals with that of the carp are about the same as those based on comparisons of the carp alpha and mammalian beta or the alpha and beta chains in mammals. These uniformities are regarded as evidence for the hypothesis that a majority of amino acid substitutions that occurred in these proteins are the result of random fixation of selectively neutral or nearly neutral mutations. TWO IMPLICATIONS OF THIS POSSIBILITY ARE DISCUSSED: (a) Random gene frequency drift is playing an important role in determining the genetic structure of biological populations and (b) genes in "living fossils" may be expected to have undergone as many DNA base (and therefore amino acid) substitutions as corresponding genes (proteins) in more rapidly evolving species.
同源蛋白质进化过程中氨基酸替换的速率非常恒定。此外，基于各种哺乳动物的α血红蛋白链与鲤鱼的α血红蛋白链的比较所估计的氨基酸替换速率，与基于鲤鱼α链与哺乳动物β链或哺乳动物α链与β链的比较所得到的速率大致相同。这些一致性被视为一种假说的证据，即这些蛋白质中发生的大多数氨基酸替换是选择性中性或近中性突变随机固定的结果。本文讨论了这种可能性的两个含义：（a）随机基因频率漂移在决定生物种群的遗传结构中起着重要作用；（b）“活化石”中的基因可能经历了与快速进化物种中相应基因（蛋白质）一样多的DNA碱基（因此也是氨基酸）替换。
