Evans D H, Lee J S, Morgan A R, Olsen R K
Can J Biochem. 1982 Feb;60(2):131-6. doi: 10.1139/o82-018.
A serious problem in the replication of repeating-sequence DNa polymers using Escherichia coli DNA polymerase I arises from the fact that this polymerase has a very strong preference for the replication of poly[d(A-T)]. Thus reactions primed with DNA containing small amounts of contaminating poly[d(A-T)] will eventually result in complete domination of the synthesis by poly[d(A-T)]. This problem can be overcome by the addition to the reaction mixture of the synthetic quinoxaline antibiotic TANDEM which binds specifically to poly[d(A-T)] completely inhibiting its replication. Using thermal denaturation experiments it can be shown that TANDEM does not bind to most other synthetic DNA polymers (e.g., poly(dA) . poly(dT) and poly[d(A-T-C)] . poly[d(G-A-T)] and therefore their replication is not inhibited. The only exception we have encountered is poly[d(T-A-C)] . poly[d(G-T-A)] which does bind TANDEM and therefore the drug cannot be used during the synthesis of this polymer. The fact that poly[d(T-A-C)] . poly[d(G-T-A)] does bind TANDEM while poly[d(A-T-C)] . poly[d(G-A-T)] does not, suggests that the drug recognizes T-A rather than A-T sequences.
利用大肠杆菌DNA聚合酶I复制重复序列DNA聚合物时存在一个严重问题，即该聚合酶对聚[d(A-T)]的复制具有很强的偏好性。因此，用含有少量污染性聚[d(A-T)]的DNA引发的反应最终会导致聚[d(A-T)]完全主导合成过程。向反应混合物中添加合成喹喔啉抗生素TANDEM可以克服这个问题，TANDEM能特异性结合聚[d(A-T)]，完全抑制其复制。通过热变性实验可以表明，TANDEM不与大多数其他合成DNA聚合物（如聚(dA)·聚(dT)和聚[d(A-T-C)]·聚[d(G-A-T)]）结合，因此它们的复制不会受到抑制。我们遇到的唯一例外是聚[d(T-A-C)]·聚[d(G-T-A)]，它确实能结合TANDEM，因此在合成这种聚合物时不能使用该药物。聚[d(T-A-C)]·聚[d(G-T-A)]能结合TANDEM而聚[d(A-T-C)]·聚[d(G-A-T)]不能，这一事实表明该药物识别的是T-A序列而非A-T序列。
