期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1981
卷号：78
期号：5
页码：2883-2887
DOI：10.1073/pnas.78.5.2883
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Circular single strands of bacteriophage phi X174 DNA are broken by rat liver DNA nicking-closing enzyme (type 1 topoisomerase) in low salt (50 mM KCl) at 37 degrees C, generating linear strands containing covalently bound enzyme [Been, M. D. & Champoux, J. J. (1980) Nucleic Acids Res. 8, 6129-6142]. The linear strands can be recircularized in the presence of 10 mM MgCl2 at 24 degrees C and 37 degrees C or 250 mM KCl at 24 degrees C. Recircularization is blocked when the hydroxyl group at the 5' terminus is phosphorylated. The linears generated by the nicking-closing enzyme can also be joined to other DNA fragments containing 5' hydroxyls, but not 5' phosphates. The linkage formed in both the intrastrand and interstrand reactions is stable to alkali. Reclosure of broken single strands is presumed to be analogous to the closure step that occurs durng nicking and closing cycles on duplex DNA.
