Bron S, Murray K, Trautner T A
Mol Gen Genet. 1975 Dec 30;143(1):13-23. doi: 10.1007/BF00269416.
All Bacillus subtilis R-type strains showing the phenomena of restriction and modification contain an endonuclease that inactivates in vitro the biological activity of a variety of DNAs lacking R-specific modification, such as transfecting SPPI, SPO2 and phi105 DNA, and transforming B. subtilis 168-type DNA. The corresponding DNAs carrying R-specific modification are resistant to the enzyme. The enzyme has been purified approximately 400-fold and is essentially free from contaminating double strand-directed unspecific exo- or endonuclease activity. Only Mg2+ is required as cofactor. The substrate DNAs are cleaved at specific sites. The double-stranded fragments produced from SPP1 DNA (molecular weight 2.5 x 10(7)) have an average molecular weight of about 3 x 10(5).
所有表现出限制与修饰现象的枯草芽孢杆菌R型菌株都含有一种核酸内切酶，该酶能在体外使多种缺乏R特异性修饰的DNA的生物活性失活，如转染的SPPI、SPO2和phi105 DNA，以及转化的枯草芽孢杆菌168型DNA。携带R特异性修饰的相应DNA对该酶具有抗性。该酶已被纯化约400倍，基本上没有污染双链定向的非特异性外切或内切核酸酶活性。仅需Mg2+作为辅因子。底物DNA在特定位点被切割。由SPP1 DNA（分子量2.5×10(7)）产生的双链片段平均分子量约为3×10(5)。
