Huang L H, Farnet C M, Ehrlich K C, Ehrlich M
Nucleic Acids Res. 1982 Mar 11;10(5):1579-91. doi: 10.1093/nar/10.5.1579.
The ability of thirty Type II restriction endonucleases to cleave five different types of highly modified DNA has been examined. The DNA substrates were derived from relatively large bacteriophage genomes which contain all or most of the cytosine or thymine residues substituted at the 5-position. These substituents were a proton (PBS1 DNA), a hydroxymethyl group (SP01 DNA), a methyl group (XP12 DNA), a glucosylated hydroxymethyl group (T4 DNA), or a phosphoglucuronated, glucosylated 4,5-dihydroxypentyl group (SP15 DNA). Although PBS1 DNA and SP01 DNA were digested by most of the enzymes, they were cleaved much more slowly than was normal DNA by many of them. 5-Methylcytosine-rich XP12 DNA and the multiply modified T4 and SP15 DNAs were resistant to most of these endonucleases. The only enzyme that cleaved all five of these DNAs was TaqI, which fragmented them extensively.
已检测了30种II型限制性内切酶切割5种不同类型高度修饰DNA的能力。DNA底物来源于相对较大的噬菌体基因组，这些基因组中所有或大部分胞嘧啶或胸腺嘧啶残基在5位被取代。这些取代基分别是一个质子（PBS1 DNA）、一个羟甲基（SP01 DNA）、一个甲基（XP12 DNA）、一个糖基化羟甲基（T4 DNA）或一个磷酸葡萄糖醛酸化、糖基化的4,5-二羟基戊基（SP15 DNA）。尽管大多数酶能消化PBS1 DNA和SP01 DNA，但其中许多酶切割它们的速度比正常DNA慢得多。富含5-甲基胞嘧啶的XP12 DNA以及多重修饰的T4和SP15 DNA对大多数这些内切酶具有抗性。唯一能切割所有这五种DNA的酶是TaqI，它能使它们大量片段化。
