Linxweiler W, Hörz W
Nucleic Acids Res. 1982 Aug 25;10(16):4845-59. doi: 10.1093/nar/10.16.4845.
The influence of the nucleotide sequence on the digestion of deoxyribonuclease 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.
人们研究了核苷酸序列对大肠杆菌脱氧核糖核酸酶消化作用的影响。结果发现，单核苷酸释放的速率以序列依赖的方式变化。C残基被迅速切割下来，G残基则缓慢切割，而A和T以中等速率释放。对合成DNA片段进行消化实验的定量分析，使得确定外切核酸酶III切割几种二核苷酸键的速率常数成为可能。发现这些值相差高达3倍。差异的累加会导致DNA链整体消化速率出现明显变化。外切核酸酶III的核苷酸特异性导致在消化过程中出现一系列离散的中间DNA片段，并在极限消化时（即所有DNA都变成单链的时刻）出现一组稳定的片段。在将该酶应用于核蛋白复合物分析时，需要考虑外切核酸酶III的这一特性。
