Rodriguez M, Bard A J
Department of Chemistry, University of Texas, Austin 78712.
Anal Chem. 1990 Dec 15;62(24):2658-62. doi: 10.1021/ac00223a002.
Cyclic voltammetric and electrogenerated chemiluminescent data were used to study the binding of tris(2,2'-bipyridine)-osmium(II), Os(bpy)3(2+), an electrostatic binder, to calf thymus DNA. The oxidized form of the osmium complex, Os(bpy)3(3+), has a stronger association to DNA than the reduced form, Os(bpy)3(2+), as indicated by the negative shift of E0' of the CV waves (K3+/K2+ = 3.35). The calculated binding constant, K2+, and binding site size, s, for the Os(byp)3(2+)-DNA system depended slightly on whether a mobile or a static equilibrium was assumed. In 10 mM NaCl, 10 mM Tris pH 7, K2+ = (7.3 +/- 0.4) x 10(3) M-1 and s = 3 base pairs (mobile) and K2+ = (5.0 +/- 0.2) x 10(3) M-1 and s = 3 base pairs (static). Electrogenerated chemiluminescence (ECL) was produced upon oxidation of Os(bpy)3(2+) at a Pt electrode in a solution containing 10 mM C2O4(2-) and 10 mM phosphate at pH 5. Addition of DNA caused a decrease in the emission intensity (I); a plot of I vs relative DNA concentration yielded K2+ = (6.5 +/- 0.5) x 10(3) M-1 and s = 3 base pairs. The osmium complex produced ECL when bound to the DNA molecule with an efficiency of 30% that of the unbound chelate.
利用循环伏安法和电化学发光数据研究了静电结合剂三（2,2'-联吡啶）锇（II），即Os(bpy)3(2+)与小牛胸腺DNA的结合。如循环伏安波的E0'负移所示（K3+/K2+ = 3.35），锇配合物的氧化形式Os(bpy)3(3+)与DNA的结合比还原形式Os(bpy)3(2+)更强。对于Os(byp)3(2+)-DNA体系，计算得到的结合常数K2+和结合位点大小s在一定程度上取决于假设的是动态平衡还是静态平衡。在10 mM NaCl、10 mM Tris pH 7中，K2+ = (7.3 ± 0.4) × 10(3) M-1且s = 3个碱基对（动态），K2+ = (5.0 ± 0.2) × 10(3) M-1且s = 3个碱基对（静态）。在pH为5、含有10 mM C2O4(2-)和10 mM磷酸盐的溶液中，在Pt电极上氧化Os(bpy)3(2+)时会产生电化学发光（ECL）。加入DNA会导致发射强度（I）降低；I对相对DNA浓度作图得到K2+ = (6.5 ± 0.5) × 10(3) M-1且s = 3个碱基对。锇配合物与DNA分子结合时产生ECL，其效率为未结合螯合物的30%。
