Goldberg A L, Wittes R E
Science. 1966 Jul 22;153(3734):420-4. doi: 10.1126/science.153.3734.420.
The pattern of organization of the genetic code decreases to a minimum the phenotypic effects of mutation and of base-pairing errors in protein synthesis. Single base changes, especially transitions, usually cause either no amino acid change or the change to a chemically similar amino acid. The degree of degeneracy of the codons for an amino acid is correlated with their guanine-cytosine content. The code gives greater protection (by both degeneracy and guaninecytosine content of codons) to those amino acids that appear more frequently in proteins. Increased reliability of the protein-synthesis system afforded by this pattern of organization nay have determined the fitness of the present code.
遗传密码的组织模式将突变和蛋白质合成中碱基配对错误的表型效应降至最低。单碱基变化，尤其是转换，通常不会导致氨基酸变化，或者只会导致变为化学性质相似的氨基酸。一种氨基酸的密码子简并程度与其鸟嘌呤 - 胞嘧啶含量相关。密码子通过简并性和鸟嘌呤 - 胞嘧啶含量，为那些在蛋白质中出现频率更高的氨基酸提供了更大的保护。这种组织模式所赋予的蛋白质合成系统更高的可靠性，可能决定了当前密码子的适应性。
