Purification and Characterization of a mammalian endoexonuclease

作者：Chantal Couture, Terry Y.-K. Chow · 发表于：Nucleic Acids Research · 年份：1992 · DOI：10.1093/nar/20.16.4355 · 被引用次数：24 · 研究领域：Bacterial Genetics and Biotechnology、DNA Repair Mechanisms、RNA and protein synthesis mechanisms

An endo-exonuclease has been purified from cultured monkey (CV-1) cells. The enzyme which was purified to near homogeneity to be a 65 kDa monomeric protein. The single-strand DNase activity is endonucleolytic and nonprocessive, whereas the double-strand DNase activity is exonucleolytic and processive. The enzyme was also found to have RNase activity using poly-rA as substrate. The pH optimum for ss-DNase is 8 and for ds-DNase it is 7.5. Both DNase activities require a divalent metal ion (Mg2+, Mn2+, Ca2+, Zn2+) for activity and exhibit the same kinetics of heat inactivation. The purified protein binds to and cleaves a synthetic Holliday junction substrate. The overall enzymatic characteristics of the mammalian protein are very similar to the putative recombination endo-exonucleases purified from Neurospora crassa, Aspergillus nidulans and Saccharomyces cerevisiae.