SEQUENCE SPECIFICITY OF EXONUCLEASE-III FROM ESCHERICHIA-COLI
SEQUENCE SPECIFICITY OF EXONUCLEASE-III FROM ESCHERICHIA-COLI
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DOI：
10.1093/nar/10.16.4845
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发表时间：
1982-01-01
影响因子：
14.9
通讯作者：
HORZ, W
中科院分区：
文献类型：
--
作者：
LINXWEILER, W;HORZ, W
研究了核苷酸序列对大肠杆菌双链特异性3 ‘ > 5 ’外脱氧核糖核酸酶III酶切DNA的影响。研究发现，单核苷酸释放的速率以序列依赖的方式变化。c残基被快速切割，g残基被缓慢切割，而A和T以中等速率释放。对合成DNA片段的酶切实验进行定量分析，可以确定外切酶III切割几种二核苷酸键的速率常数。人们发现这些值的差异可达3倍。这些差异的总和可以导致DNA链消化的总体速率的明显变化。外切酶III的核苷酸特异性导致在消化过程中短暂出现一系列离散的DNA片段，而在极限消化中出现一组稳定的片段，即当所有DNA都变成单链时。在分析核蛋白复合物时，需要考虑到外切酶III的这一特性。
The influence of the nucleotide sequence on the digestion of DNA by exonuclease III, a double strand specific 3′↠5′ exodeoxyribonuclease from E. coli, has been investigated. It was found that the rate at which mononucleotides are released varies in a sequence dependent fashion. C-residues are cleaved off rapidly and G-residues slowly while A and T are released at an intermediate rate. Quantitative analyses of digestion experiments with synthetic DNA fragments made it possible to determine rate constants for the cleavage of several dinucleotide bonds by exonuclease III. These values were found to differ by up to a factor of 3. Summation of the differences can lead to appreciable variation in the overall rate of digestion of a DNA strand. The nucleotide specificity of exonuclease III leads to a transient appearance of a series of discrete DNA fragments intermediate in digestion and a stable set of fragments in limit digests, i.e. at the point when all DNA has become single-stranded. This property of exonuclease III needs to be taken into account for the application of the enzyme in the analysis of nucleoprotein complexes.