Brockes J P, Brown P R, Murray K
Biochem J. 1972 Mar;127(1):1-10. doi: 10.1042/bj1270001.
The bacteriophage P1 modification enzyme, assayed by the specific methylation of unmodified bacteriophage 82 DNA, has been purified 500-fold from a bacteriophage P1 lysogen of Escherichia coli. The enzyme catalyses the incorporation of approximately 20-24 methyl groups per bacteriophage 82 DNA molecule. The sole product of methylation is 6-methylaminopurine. Methylation of unmodified bacteriophage DNA confers protection against a challenge by purified bacteriophage P1 restriction enzyme. The pH optimum is 6.0-6.25: the apparent K(m) for S-adenosyl-l-methionine is 5x10(-6)m.
通过未修饰的噬菌体82 DNA的特异性甲基化来测定的噬菌体P1修饰酶，已从大肠杆菌的噬菌体P1溶原菌中纯化了500倍。该酶催化每个噬菌体82 DNA分子掺入约20 - 24个甲基基团。甲基化的唯一产物是6 - 甲基氨基嘌呤。未修饰的噬菌体DNA的甲基化赋予其对纯化的噬菌体P1限制酶攻击的抗性。最适pH为6.0 - 6.25：S - 腺苷 - L - 甲硫氨酸的表观K(m)为5×10(-6)m。
