COUPLED KINETIC-ANALYSIS OF CLEAVAGE OF DNA BY ESPERAMICIN AND CALICHEAMICIN
COUPLED KINETIC-ANALYSIS OF CLEAVAGE OF DNA BY ESPERAMICIN AND CALICHEAMICIN
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DOI：
10.1021/ja00014a040
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发表时间：
1991-07-03
影响因子：
15
通讯作者：
DABROWIAK, JC
中科院分区：
文献类型：
--
作者：
KISHIKAWA, H;JIANG, YP;DABROWIAK, JC
偶联动力学分析esperamicin，加利车霉素，和DNase I切割共价闭合的环状PM2 DNA已进行。琼脂糖凝胶电泳实验的光密度数据的分析表明，埃斯波霉素Al，像水解酶DNA酶I，主要产生单链断裂的DNA。这些试剂导致共价闭合的环状I型DNA最初转化为切口环状II型DNA。然而，该过程的速率常数（k1 '）与II型DNA转化为线性III型DNA的速率常数（k2'）之比与完全随机的切口不一致，并且可能发生一些双链切割。DNase Ⅰ和esperamicin A1的k1 ′/k2 ′值分别为5.4和3.9。这些试剂的行为与esperamicin C和加利车霉素的行为形成鲜明对比，从分析中推断出DNA的双链切割。尽管加利车霉素在DNA中引入第一断裂的速率常数低于埃斯波霉素C的相应速率常数，但加利车霉素的第二断裂（在相对链中）快，使其成为更好的双链切割剂。这些药物在抗肿瘤剂中是独特的，因为弹头部分上的单个激活事件在DNA中产生双链断裂，而不需要用其他试剂后处理DNA以诱导切割。在这些不寻常的抗癌药物的结构差异方面的裂解动力学进行了讨论。
A coupled kinetic analysis of esperamicin, calicheamicin, and DNase I cleavage of covalently closed circular PM2 DNA has been carried out. Analysis of the optical density data derived from agarose gel electrophoresis experiments shows that esperamicin Al, like the hydrolytic enzyme DNase I, produces mainly single-strand breaks in DNA. These agents cause covalently closed circular form I DNA to be initially converted to nicked circular form II DNA. However, the ratio of the rate constant for this process (k1') to that associated with conversion of form II to linear form III DNA (k2') is not consistent with completely random nicking, and some double-strand cleavage may occur. The values of k1'/k2' found for DNase I and esperamicin A1 were 5.4 nd 3.9, respectively. The behavior of these agents sharply contrasts with that of esperamicin C and calicheamicin, for which double-strand cleavage of DNA is deduced from the analysis. Although the rate constant for introducing the first break in DNA for calicheamicin is lower than the corresponding rate constant for esperamicin C, the second break (in the opposing strand) is fast for calicheamicin, making it the better double-strand cleaving agent. These drugs are unique among antitumor agents in that a single activation event on the warhead portion produces a double-strand break in DNA without the need to posttreat the DNA with other agents in order to induce a cleavage. The cleavage kinetics are discussed in terms of the structural differences in these unusual anticancer drugs.