大肠杆菌和枯草杆菌的L-ter 到起始密码子的距离分析

基于第一ATG规则，分别对确定基因和不确定基因的L-ter到起始密码子(ATG、GTG或TTG)的距离和L-ter到起始密码子下游紧邻的ATG的距离进行统计，结果表明：L-ter到起始密码子的距离主要分布在20个氨基酸以内；在以第一ATG和第一GTG为起始密码子的基因中，L-ter到起始密码子下游紧邻的ATG是L-ter到起始密码子平均距离的4～5倍。这些可能是起始密码子的重要位置特征，也说明了少数基因以GTG起始的原因．对于不满足第一ATG、GTG规则的基因，分析了L-ter到起始密码子之间出现ATG、GTG和TTG的比率，发现大肠杆菌的不确定基因与确定基因之间有较大的差别，而枯草杆菌的差别不大．

An Analysis of the Distance from L-ter to the Start Codon for E.coli and B.sub

Based on the first ATG rule,the distance from L-ter to the start codon (ATG,GTG or TTG) and that from L-ter to the ATG downstream next to the start codon are analyzed for certain genes and uncertain genes.The results show that the distance from L-ter to the start codon mainly distributes in the range of 20 amino acids;Among the genes with the start codon of the first ATG and first GTG,the average distance between L-ter and the ATG downstream adjacent to the start codon is 4~5 times of that between L-ter and the start codon.These may be a character of the start codon.Meanwhile,the property shows the reason why minority genes start with GTG.As for the genes disobeying the first ATG and first GTG rule,their appearance rates of ATG,GTG and TTG between L-ter and the start codon are analyzed.The rates in uncertain genes are different from that in certain genes for E.coli,but the difference for B.sub is small.