Sista H S, Loder R T, Caruthers M H
Nucleic Acids Res. 1979 Jun 11;6(7):2583-99. doi: 10.1093/nar/6.7.2583.
Chemical and enzymatic methods were used to synthesize a transition (AT to GC) and a transversion (AT to TA) at a lac operator site known to interact with lac repressor through the thymine 5 methyl group. These operators also contained a poly(dA) . poly(dT) tail 8 to 12 base pairs in length at one end. Results suggest that the steric constraints of lac repressor relative to the position of the 5 methyl group are quite critical. For example a seven fold reduction in stability was observed for the transversion. Results also suggest that the operator spans at least 21 base pairs.
采用化学和酶促方法，在已知通过胸腺嘧啶5-甲基基团与乳糖阻遏物相互作用的乳糖操纵基因位点合成了一个转换（AT到GC）和一个颠换（AT到TA）。这些操纵基因在一端还含有一个长度为8至12个碱基对的聚（dA）·聚（dT）尾。结果表明，乳糖阻遏物相对于5-甲基基团位置的空间限制非常关键。例如，观察到颠换的稳定性降低了七倍。结果还表明，操纵基因跨度至少为21个碱基对。
