Joseph J W, Kolodner R
J Biol Chem. 1983 Sep 10;258(17):10418-24.
Exonuclease VIII from Escherichia coli was shown to preferentially degrade linear duplex DNA, although a limited amount of activity with single-stranded linear DNA substrates was detected. No nucleolytic activity was observed with double-stranded circular substrates containing single strand breaks or gaps. Exonuclease VIII was shown to degrade linear duplex DNA from the 5' termini of the molecules and proceed in the 5' to 3' direction via a processive reaction mechanism. Initiation could occur from either a 5'-hydroxyl or 5'-phosphate residue at equal rates. The products of degradation of linear duplex DNA were an equivalent amount of 5'-mononucleotides and single-stranded DNA. Possible roles for exonuclease VIII in genetic recombination are discussed.
已证明来自大肠杆菌的核酸外切酶VIII优先降解线性双链DNA，不过也检测到其对单链线性DNA底物有有限的活性。对于含有单链断裂或缺口的双链环状底物，未观察到核酸水解活性。核酸外切酶VIII可从分子的5'末端开始降解线性双链DNA，并通过连续反应机制沿5'至3'方向进行。起始可从5'-羟基或5'-磷酸残基以相同速率发生。线性双链DNA降解的产物是等量的5'-单核苷酸和单链DNA。文中讨论了核酸外切酶VIII在基因重组中的可能作用。
