KINETIC AND EQUILIBRIUM BINDING-STUDIES OF ACTINOMYCIN-D WITH SOME D(TGCA)-CONTAINING DODECAMERS
KINETIC AND EQUILIBRIUM BINDING-STUDIES OF ACTINOMYCIN-D WITH SOME D(TGCA)-CONTAINING DODECAMERS
复制标题
DOI：
10.1021/bi00406a008
复制
发表时间：
1988-03-22
期刊：
影响因子：
2.9
通讯作者：
CHEN, FM
中科院分区：
文献类型：
--
作者：
CHEN, FM
放线菌素D（ACTD）与d（ATATACGTATAT）、四种含d（TGCA）的十二聚体和聚（dG-dC）的比较动力学、解链和平衡结合研究。poly（dG-dC）揭示了（1）ACTD对dC-dG序列的亲和力远小于对dG-dC序列的亲和力;（2）ACTD分别与d（TATATGCATATA）和d（TATGCATGCATA）形成1：1和2：1药物-双链体复合物，并且它们的SDS驱动的解离表现出速率为（apx. 5倍。10-4 s-1，20 °。C）略慢于聚（dG-dC）.聚（dG-dC）;（3）虽然d（CATGCATGCATG）的解链温度比d（TATGCATGCATA）的解链温度高8-9 ℃，但ACTD从这两种寡聚体上解离的速率差别不大，结合常数为（1-5）× 10 - 6。（4）ACTD与双链体d-（TGCATGCATGCA）的结合显示出3：1的化学计量比，并且复合物以两个特征时间解离，快速组分（1/k = apprx. 100 s），包括2/3的贡献和慢过程（约100 s）。2000 s）贡献了另外的1/3;和（5）低聚物的缓慢解离动力学似乎与通过不停流技术可检测到的更高百分比的缓慢缔合动力学相关。这些结果表明，d（TGCA）序列比d（CGCG）序列具有更强的结合力和更慢的解离位点，并表明dG-dC插入位点侧翼的碱基对可能调节ACTD的五肽环与DNA小沟的相互作用。ACTD从d-（TGCATGCATGCA）中近端dG-dC位点的快速解离最有可能是由于其中一个五肽环不能牢固地锚，这是末端磨损效应的结果。
Comparative kinetic, melting, and equilibrium binding studies of actinomycin D (ACTD) with d(ATATACGTATAT), four d(TGCA)-containing dodecamers, and poly(dG-dC) .cntdot. poly(dG-dC) revealed that (1) the affinity of ACTD for the dC-dG sequence is much less than for the dG-dC sequence; (2) ACTD forms 1:1 and 2:1 drug-duplex complexes with d(TATATGCATATA) and d(TATGCATGCATA), respectively, and their SDS driven dissociations exhibit single-exponential characteristics with rates (.apprx. 5 .times. 10-4 s-1 at 20.degree. C) slightly slower than that of poly(dG-dC) .cntdot. poly(dG-dC); (3) although the melting temperature of d(CATGCATGCATG) is 8-9 deg higher than that of d(TATGCATGCATA), the rates of ACTD dissociation from these two oligomers are not greatly different and binding constants of (1-5) .times. 107 M-1 have been estimatd for both; (4) a 3:1 stoichiometry is exhibited by ACTD binding to duplex d-(TGCATGCATGCA) and the complex dissociates with two characteristic times, the fast component (1/k = .apprx. 100 s) comprising 2/3 of the contribution and the slow process (.apprx. 2000 s) contributing the other 1/3; and (5) the slow dissociation kinetics of an oligomer appears to be correlated to the higher percentage of slow association kinetics detectable by non-stop-flow techniques. These results indicate that the d(TGCA) sequence is a stronger binding and a slower dissociation site than the d(CGCG) sequence and suggest that base pairs flanking the dG-dC intercalative site may modulate interactions of the pentapeptide rings of ACTD with the DNA minor groove. The fast ACTD dissociation from the near-end dG-dC sites in d-(TGCATGCATGCA) is most likely due to the inability of one of the pentapeptide rings to anchor securely, a consequence of end-fraying effects.