大肠杆菌编码序列碱基片段的统计分析

对大肠杆菌基因１２３１个编码开始区和１３０７个编码终止区域内的６三基片段，４碱基片段和３碱基处段进行了统计，发现６碱基片段模式数的对民其相对频率成线性下降关系，绝大多数４碱基和３碱基片段出现在相对频率于２的范围之内；编码区出现最多的碱基片段是多聚Ａ；

The Statistical Analyses of Base Elements for E.coli Coding Sequences

code starting sequences and 1 307 code terminal sequences of E.coli are compiled and 6 base modes, 4 base modes and 3 base modes in the two regions are counted. It is found that there is a good linear relation between the logarithm of 6 base mode number and its relative frequency (RF); most 4 base modes and 3 base modes are in the region of RF<2 . The most appeared base elements in coding region is poly A; the base modes in code starting region and code-terminal region have distinct differences; the base modes of GGA category in code starting region are rare modes, but these modes are optimum in SD region. In coding region, TAG and CTA modes are forbidden. In addition, the relative frequencies of 4 base and 3 base modes have distinct relation with the gene expression level, the relative frequencies of most base elements which have high RF value are increased when the gene expressed level is raised.