CORALYNE BINDS TIGHTLY TO BOTH T.A.T-CONTAINING AND C.G.C+-CONTAINING DNA TRIPLEXES
CORALYNE BINDS TIGHTLY TO BOTH T.A.T-CONTAINING AND C.G.C+-CONTAINING DNA TRIPLEXES
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DOI：
10.1021/bi00072a014
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发表时间：
1993-06-01
期刊：
影响因子：
2.9
通讯作者：
HAMPEL, KJ
中科院分区：
文献类型：
--
作者：
LEE, JS;LATIMER, LJP;HAMPEL, KJ
Coralyne是一种DNA结合的抗肿瘤抗生素，其结构包含四个稠合芳环。用三种技术研究了珊瑚碱与DNA三链体poly（dT）、poly（dA）、poly（dT）和poly[d（TC）]、poly-[d（GA）]、poly[d（C+T）]的相互作用。首先，通过热变性分析测量T（m）值。在结合coralyne后，两种三链体显示T（m）值比相应的双链体增加更多。一种相关的药物，berberinium，其中一个芳香环是部分饱和的，在T（m）中的变化要小得多。第二，在DNA存在下，coralyne的荧光被淬灭，允许通过Scatchard分析测量结合参数。的结合等温线是双相的，这是解释在强插层结合和弱得多的堆叠相互作用。在2 mM Mg ~（2+）存在下，与poly（dT）.poly-（dA）.poly（dT）和poly[d（TC）].poly[d（GA）].poly [d（C+T）]的结合常数分别为3.5 × 10 ~（6）M ~（-1）和1.5 × 10 ~（6）M ~（-1），而与亲本双链体的亲和力至少低2个数量级。在不存在2 mM Mg ~（2+）的情况下，poly[d（TC）].poly[d（GA）].poly[d（C+T）]和poly-[d（TC）].poly[d（GA）]的结合常数分别为40 × 10 ~（6）M ~（-1）和15 × 10 ~（6）M ~（-1）。因此，珊瑚碱显示出对三链体结构的相当大的偏好，但序列特异性很小，不像乙锭，乙锭仅结合聚（dT）、聚（dA）-聚（dT）。进一步的证据为嵌入coralyne提供了在260 nm处的相对荧光量子产率的增加后，结合coralyne的三链体，以及在Fe[（CN）6]4-的存在下的荧光猝灭的情况下。第三，coralyne促进含有pyr.pur道和单链聚嘧啶的质粒之间的分子间三链体形成。珊瑚碱结合三链体的能力可能与其体内活性有关，也提示了设计具有序列特异性的三链体结合药物的方法。
Coralyne is a DNA-binding antitumor antibiotic whose structure contains four fused aromatic rings. The interaction of coralyne with the DNA triplexes poly(dT).poly(dA).poly(dT) and poly[d(TC)].poly-[d(GA)].poly[d(C+T)] was investigated by using three techniques. First, T(m) values were measured by thermal denaturation analysis. Upon binding coralyne, both triplexes showed T(m) values that were increased more than those of the corresponding duplexes. A related drug, berberinium, in which one of the aromatic rings is partially saturated, gave much smaller changes in T(m). Second, the fluorescence of coralyne is quenched in the presence of DNA, allowing the measurement of binding parameters by Scatchard analysis. The binding isotherms were biphasic, which was interpreted in terms of strong intercalative binding and much weaker stacking interactions. In the presence of 2 mM Mg2+, the binding constants to poly(dT).poly-(dA).poly(dT) and poly[d(TC)].poly[d(GA)].poly[d(C+T)] were 3.5 X 10(6) M-1 and 1.5 X 10(6) M-1, respectively, while the affinity to the parent duplexes was at least 2 orders of magnitude lower. In the absence of 2 mM Mg2+, the binding constants to poly[d(TC)].poly[d(GA)].poly[d(C+T)] and poly-[d(TC)].poly[d(GA)] were 40 X 10(6) M-1 and 15 X 10(6) M-1, respectively. Thus coralyne shows considerable preference for the triplex structure but little sequence specificity, unlike ethidium, which will only bind to poly(dT).poly(dA)-poly(dT). Further evidence for intercalation of coralyne was provided by an increase in the relative fluorescence quantum yield at 260 nm upon binding of coralyne to triplexes as well as an absence of quenching of fluorescence in the presence of Fe[(CN)6]4-. Third, coralyne promoted intermolecular triplex formation between plasmids containing a pyr.pur tract and a single-stranded polypyrimidine. The ability of coralyne to bind to triplexes may relate to its in vivo activity and also suggests ways of designing triplex-binding drugs with sequence specificity.