Grondal-Zocchi G, Verly W G
Biochem J. 1985 Jan 15;225(2):535-42. doi: 10.1042/bj2250535.
Deoxyribonuclease IV, a 5'-3' exonuclease degrading double-stranded DNA from intra-strand nicks, has been purified from the chromatin of rat liver cells. The enzyme, which has an Mr of 58000, excises the apurinic (AP) sites from a depurinated DNA nicked 5' to these AP sites with the chromatin AP endonuclease. The excision is not the result of hydrolysis of the phosphodiester bond 3' to the AP sites since the excision product does not behave as deoxyribose 5-phosphate but as its 2,3-unsaturated derivative. This result suggests that, to remove the AP sites from the DNA nicked by an AP endonuclease, the chromatin deoxyribonuclease IV rather acts as a catalyst of beta-elimination.
脱氧核糖核酸酶IV是一种5'-3'核酸外切酶，可从链内切口处降解双链DNA，已从大鼠肝细胞的染色质中纯化出来。该酶的分子量为58000，它与染色质脱嘌呤嘧啶（AP）内切酶一起，从位于这些AP位点5'端的脱嘌呤DNA切口处切除AP位点。这种切除不是AP位点3'端磷酸二酯键水解的结果，因为切除产物的行为不像5-磷酸脱氧核糖，而是其2,3-不饱和衍生物。这一结果表明，为了从由AP内切酶切割的DNA中去除AP位点，染色质脱氧核糖核酸酶IV更像是β-消除反应的催化剂。
