White R J, Phillips D R
Department of Biochemistry, La Trobe University, Bundoora, Victoria, Australia.
Biochem Pharmacol. 1989 Jan 15;38(2):331-4. doi: 10.1016/0006-2952(89)90045-2.
The rate of dissociation of actinomycin D from DNA was measured by sodium dodecyl sulphate (SDS) sequestration (37 degrees) from calf thymus DNA and a 24 base pair (bp) synthetic DNA containing one high affinity AGCT site for the drug. The time constants were 276 and 142 sec, respectively, and suggest a stabilising effect though positive cooperativity in heterogenous DNA, or from specific neighbouring sequences. The time constant for dissociation of actinomycin D from the AGCT site was 2900 sec as measured by an in vitro transcription assay at 37 degrees, and suggests that, under conditions of active transcription of the DNA, the drug-DNA complex has additional stabilising contributions, possibly by a cage effect from RNA polymerase, or by additional drug-RNA polymerase contacts.
通过十二烷基硫酸钠（SDS）螯合（37摄氏度），从小牛胸腺DNA和一个含有该药物的一个高亲和力AGCT位点的24碱基对（bp）合成DNA中，测量放线菌素D从DNA上的解离速率。时间常数分别为276秒和142秒，这表明在异源DNA中或来自特定相邻序列中，通过正协同作用有稳定作用。在37摄氏度下通过体外转录测定法测得，放线菌素D从AGCT位点解离的时间常数为2900秒，这表明在DNA的活跃转录条件下，药物-DNA复合物有额外的稳定作用，可能是通过RNA聚合酶的笼效应，或通过额外的药物-RNA聚合酶接触。
