Denny W A, Wakelin L P
Cancer Research Laboratory, University of Auckland School of Medicine, New Zealand.
Anticancer Drug Des. 1987 Aug;2(1):71-7.
Viscometric measurements using covalently closed-circular DNA and sonicated rod-like fragments of calf thymus DNA show that the DNA-binding anti-cancer drug bisantrene intercalates with a helix unwinding angle of 14 degrees, and causes an increase in DNA contour length of 2.8A per bound drug molecule. Measurements of DNA affinity using the ethidium displacement method indicate binding constants of 7-8 X 10(7) M-1 for both natural and synthetic DNAs in buffer of ionic strength 0.1. The bimolecular rate constant for association with calf thymus DNA is greater than 1 X 10(7)M-1 s-1 at 20 degrees C and ionic strength 0.1, as determined by stopped-flow spectrophotometry. Surfactant sequestration studies of the dissociation of bisantrene from both calf thymus and synthetic DNAs reveal that the mechanism is complex, involving at least three distinguishable processes in all cases. The kinetic profiles are found to be essentially independent of DNA type, with average reciprocal time constants in the range 1-3 s-1 at a binding ratio of one drug molecule per 20 base pairs in buffer of ionic strength 0.1 at 20 degrees C. These results are discussed with respect to the mechanism of binding of bisantrene to DNA.
使用共价闭合环状DNA和小牛胸腺DNA的超声破碎棒状片段进行的粘度测量表明，与DNA结合的抗癌药物双胺苯吖啶以14度的螺旋解旋角嵌入，并使每个结合的药物分子导致DNA轮廓长度增加2.8埃。使用溴化乙锭置换法测量DNA亲和力表明，在离子强度为0.1的缓冲液中，天然和合成DNA的结合常数均为7 - 8×10⁷ M⁻¹。通过停流分光光度法测定，在20℃和离子强度0.1时，与小牛胸腺DNA结合的双分子速率常数大于1×10⁷ M⁻¹ s⁻¹。对双胺苯吖啶从小牛胸腺DNA和合成DNA解离的表面活性剂螯合研究表明，其机制很复杂，在所有情况下至少涉及三个可区分的过程。发现在离子强度0.1、20℃的缓冲液中，每20个碱基对结合一个药物分子的结合比下，动力学曲线基本上与DNA类型无关，平均倒数时间常数在1 - 3 s⁻¹范围内。针对双胺苯吖啶与DNA结合的机制对这些结果进行了讨论。
