Wang J
Chemical Engineering Research Center, Tianjin University, China.
J Biomol Struct Dyn. 1998 Aug;16(1):51-7. doi: 10.1080/07391102.1998.10508226.
The distribution of the occurrence frequencies of each of the four bases at the first, second and third codon positions and in the total coding sequences is analyzed by a graphic method. It is shown that for the coding sequences of 90 species, A has its largest frequency at the second codon position and the smallest one at the third position. C and U have their least frequencies at the first codon position, while G has its largest frequency at the first codon position. By this method, we also find that for each base, there is positive correlation between every two frequencies of the base in the first, second, third and the total coding sequences for 90 species. For each of the four bases, the correlation between the frequencies at the third codon position and that in the total coding sequences is more prominent than others. A statistical method is used to give a precise description of the correlation for the frequencies of every base and it is found that the conclusions drawn by the graphic method are consistent with that got by the statistical method.
通过一种图形方法分析了四个碱基在第一、第二和第三密码子位置以及在总编码序列中各自出现频率的分布情况。结果表明，对于90种物种的编码序列，A在第二密码子位置的频率最高，在第三密码子位置的频率最低。C和U在第一密码子位置的频率最低，而G在第一密码子位置的频率最高。通过这种方法，我们还发现对于每个碱基，在90种物种的第一、第二、第三和总编码序列中，该碱基的任意两个频率之间都存在正相关。对于四个碱基中的每一个，第三密码子位置的频率与总编码序列中的频率之间的相关性比其他情况更为显著。使用一种统计方法对每个碱基频率的相关性进行了精确描述，发现图形方法得出的结论与统计方法得出的结论一致。
