氨基酸间的距离与蛋白质进化的随机模型

Distances among Amino Acids and Stochastic Model of Protein Evolution

用遗传密码词典中61个密码作为链的状态,提出了一个氨基酸替代的马氏链模型。将20种氨基酸间首次通过时间作为突变距离与 Grantham(1974)的氨基酸间理化距离以及Dayhoff(1978)的相对替代概率做相关分析。结果表明,替代概率与理化距离的相关大大高于与突变距离间的相关,说明蛋白质进化过程中,是自然选择而非突变起着决定性作用。

A Markov chain model for the evolution of protein was pressented with the 61 codons cor- responding to the states of the chain.The mean first passage time between amino acids was used as muta- tional distance(d_3)to perform correlation analysis with the physicochemical distance(d_2)of Grantham (1974)and the relative mutation probability(d_1)of Dayhoff et al.(1978).The results showed that d_1 is much more highly correlated with d_2 than with d_3,implying that selection rather than mutation must have played a determining role in protein evolution.