1H NMR studies of tris(phenanthroline) metal complexes bound to oligonucleotides: characterization of binding modes.
1H NMR studies of tris(phenanthroline) metal complexes bound to oligonucleotides: characterization of binding modes.
复制标题
与寡核苷酸结合的三（菲咯啉）金属配合物的 1 H NMR 研究：结合模式的表征。
DOI：
10.1021/bi00459a006
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Barton,JK
中科院分区：
文献类型：
--
作者：
Rehmann,JP;Barton,JK
哥伦比亚大学化学系，纽约，纽约10027，1989年6月30日接收; 1989年10月19日接收修订版摘要：Ru（phen）32+、Rh（phen）33+和Co（phen）33+与寡核苷酸d（GTGCAC）2和5的结合，用核磁共振谱研究了-pd（CGCGCG）_2与温度、浓度和金属配合物手性的关系。双链体寡核苷酸作为金属络合物的手性位移试剂;与每种对映体相关的菲咯啉质子在结合到寡聚体上时被解析。的光谱滴定，与physical研究一致，表明配合物结合的低聚物通过两种模式：一个分配为有利于插层异构体，和其他分配为有利于异构体的表面结合的相互作用。配体质子的扰动的方式，这意味着特定的质子结合模式的敏感性，具体地说，H4，7质子似乎是改变最多的对映异构体，而H5，6质子的扰动更多的对映异构体。的NMR化学位移的变化似乎特别敏感，这种表面结合的相互作用，其中，Ru（phen）32+的结合和生物物理参数的比较的基础上，出现更强的结合寡核苷酸比多核苷酸。相对于寡核苷酸质子位移，腺嘌呤H2质子，位于小沟的螺旋，显示最大的高场位移与金属结合，更显着的异构体。大沟胸腺嘧啶甲基质子（TMe）向低场移动的程度较小，更是如此的异构体。不同的结合模式也不同，就其动力学的协会;纵向弛豫速率的-和-4，7菲咯啉质子的Rh（phen）33+分别为0.88和1.14秒，在d（GTGCAC）2的存在下。与取代惰性金属络合物的研究相反，外消旋Co（phen）33+添加到寡核苷酸溶液中产生不相等的对映体群体，这是由于在低聚物存在下钴络合物的快速外消旋化和重新平衡到有利于结合的形式。还通过核磁共振光谱法监测了双链体熔融;复合物使双链体熔融温度提高约5 ℃。在Co（phen）33+的情况下，随着温度升高，随着螺旋熔化，发生对映体的再平衡，这表明，手性歧视来自对映选择性相互作用与螺旋，而不是与单链寡核苷酸。了解小的天然产物如何以序列特异性结合DNA以及也可以靶向特定DNA位点的新合成分子的合理设计（Dervan，一九八八年; Hecht，1986年; Zein等人，1988年）。在我们的实验室中，我们集中于过渡金属化学在基于形状选择的特异性结合和切割DNA的分子设计中的应用（巴顿，1986;弗莱托等人，1988; Pyle等人，1989年a）。特别地，我们已经将我们的努力集中在三（菲咯啉）金属络合物的衍生物上（Mei &巴顿，1988; Kirshenbaum等人，1988年）。
Department of Chemistry, Columbia University, New York, New York 10027 Received June 30, 1989; Revised Manuscript Received October 19, 1989 abstract: The binding of Ru (phen) 32+, Rh (phen) 33+, and Co (phen) 33+ to the oligonucleotides d (GTGCAC) 2 and 5,-pd (CGCGCG) 2 has been examined by NMR spectroscopy as a function of temperature, con-centration, and chirality of the metal complex. The duplex oligonucleotides act as chiral shift reagents for the metal complexes; phenanthroline protons associated with each enantiomer are resolved upon binding to the oligomer. The spectral titrations, consistent with photophysical studies, indicate that the complexes bind to the oligomer through two modes: one assigned as intercalation favoring the-isomer, and the other assigned as the surface-bound interaction favoring the-isomer. The ligand protons are perturbed in a manner that implies sensitivity of particular protons to binding mode; specifically, the H4, 7 protons appear to be altered most for the-enantiomer while the H5, 6 protons are perturbed more for the-enantiomer. The NMR chemical shift variations appear particularly sensitive to this surface-bound interaction, which, on the basis of a comparison of binding and photophysical parameters for Ru (phen) 32+, appears more prominant in binding to oligonucleotides than that to polynucleotides. With respect to oligonucleotide proton shifts, the adenine H2 proton, positioned in the minor groove of the helix, shows the largest upfield shifts with metal binding, and more dramatically with-isomers. The major groove thymine methyl protons (TMe) shift downfield to a lesser extent, and more so for-isomers. The different binding modes also differ with respect to their dynamics of association; the longitudinal relaxation rates of-and-4, 7 phenanthroline protons of Rh (phen) 33+ are 0.88 and 1.14 s, respectively, in the presence of d (GTGCAC) 2. In contrast to studies with the substitutionally inert metal complexes, addition of racemic Co (phen) 33+ to the oligonucleotide solution yields unequal populations of enantiomers, owing to the rapid racemization of the cobalt complex in the presence of oligomer and reequilibration to that form which favors binding. Duplex melting has also been monitored by NMR spectroscopy; the complexes increase the duplex melting temperature by~ 5 C. In the case of Co (phen) 33+, with increasing temperature, as the helix melts, a reequlibration of the enantiomers occurs, indicating that the chiral discrimination arises from enantioselective interactionswith the helix rather thanwith the single-stranded oligonucleotides.There has been considerable attention focused on the un-derstanding of how smallnatural products bind DNA with sequence specificity and on the rational design of new synthetic molecules that may also be targeted to specific DNA sites (Dervan, 1988; Hecht, 1986; Zein et al., 1988). In our laboratory we have concentrated on the application of transition metal chemistry to the design of molecules that bindand cleave DNA with specificity based upon shape selection (Barton, 1986; Fleisher et al., 1988; Pyle et al., 1989a). In particular, we have focused our efforts on derivatives of tris (phenanthroline) metalcomplexes (Mei & Barton, 1988; Kirshenbaum et al., 1988).