Frank Natia L, Meade Thomas J
California Institute of Technology, The Beckman Institute 139-74, Pasadena, California 91125, USA.
Inorg Chem. 2003 Feb 24;42(4):1039-44. doi: 10.1021/ic025567q.
Incorporation of metalated nucleosides into DNA through covalent modification is crucial to measurement of thermal electron-transfer rates and the dependence of these rates with structure, distance, and position. Here, we report the first synthesis of an electron donor-acceptor pair of 5' metallonucleosides and their subsequent incorporation into oligonucleotides using solid-phase DNA synthesis techniques. Large-scale syntheses of metal-containing oligonucleotides are achieved using 5' modified phosporamidites containing Ru(acac)(2)(IMPy) (acac is acetylacetonato; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (3) and Ru(bpy)(2)(IMPy) (bpy is 2,2'-bipyridine; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (4). Duplexes formed with the metal-containing oligonucleotides exhibit thermal stability comparable to the corresponding unmetalated duplexes (T(m) of modified duplex = 49 degrees C vs T(m) of unmodified duplex = 47 degrees C). Electrochemical (3, E(1/2) = -0.04 V vs NHE; 4, E(1/2) = 1.12 V vs NHE), absorption (3, lambda(max) = 568, 369 nm; 4, lambda(max) = 480 nm), and emission (4, lambda(max) = 720 nm, tau = 55 ns, Phi = 1.2 x 10(-)(4)) data for the ruthenium-modified nucleosides and oligonucleotides indicate that incorporation into an oligonucleotide does not perturb the electronic properties of the ruthenium complex or the DNA significantly. In addition, the absence of any change in the emission properties upon metalated duplex formation suggests that the Ru(bpy)(2)(IMPy)Ru(acac)(2)(IMPy) pair will provide a valuable probe for DNA-mediated electron-transfer studies.
通过共价修饰将金属化核苷掺入DNA对于测量热电子转移速率以及这些速率与结构、距离和位置的依赖性至关重要。在此，我们报道了5'金属核苷的电子供体-受体对的首次合成，以及随后使用固相DNA合成技术将其掺入寡核苷酸中。使用含有Ru(acac)(2)(IMPy)（acac为乙酰丙酮；IMPy为2'-亚氨基甲基吡啶基-2'-脱氧尿苷）(3)和Ru(bpy)(2)(IMPy)（bpy为2,2'-联吡啶；IMPy为2'-亚氨基甲基吡啶基-2'-脱氧尿苷）(4)的5'修饰亚磷酰胺实现了含金属寡核苷酸的大规模合成。由含金属寡核苷酸形成的双链体表现出与相应未金属化双链体相当的热稳定性（修饰双链体的T(m)=49℃，未修饰双链体的T(m)=47℃）。钌修饰核苷和寡核苷酸的电化学（3，E(1/2)=-0.04 V vs NHE；4，E(1/2)=1.12 V vs NHE）、吸收（3，λ(max)=568、369 nm；4，λ(max)=480 nm）和发射（4，λ(max)=720 nm，τ=55 ns，Φ=1.2×10(-4)）数据表明，掺入寡核苷酸不会显著干扰钌配合物或DNA的电子性质。此外，金属化双链体形成后发射性质没有任何变化，这表明Ru(bpy)(2)(IMPy)Ru(acac)(2)(IMPy)对将为DNA介导的电子转移研究提供有价值的探针。
