Vovis G F, Horiuchi K, Zinder N D
Proc Natl Acad Sci U S A. 1974 Oct;71(10):3810-3. doi: 10.1073/pnas.71.10.3810.
The restriction endonuclease from E. coli B is both an endonuclease and a DNA methylase. Both activities either require or are stimulated by Mg(+2), adenosine triphosphate, and S-adenosyl-L-methionine. The particular activity which the enzyme exhibits depends upon the nature of the SB sites, the genetic sites that identify substrate DNA. Enzymatic treatment of DNA that has an unmodified, wild-type SB site results in either rapid restriction of the DNA or very slow methylation of the SB site. On the other hand, a hybrid SB site (modified), which protects the DNA molecule from restriction, results in rapid methylation of that SB site.
来自大肠杆菌B的限制性内切核酸酶既是一种内切核酸酶，也是一种DNA甲基化酶。这两种活性都需要Mg(+2)、三磷酸腺苷和S-腺苷-L-甲硫氨酸，或者受到它们的刺激。该酶所表现出的特定活性取决于SB位点的性质，SB位点是识别底物DNA的基因位点。用酶处理具有未修饰的野生型SB位点的DNA，会导致DNA快速被限制或SB位点非常缓慢地甲基化。另一方面，一个能保护DNA分子不被限制的杂交SB位点（已修饰），会导致该SB位点快速甲基化。
