Synthesis and DNA binding properties of bioorganometallic (η5-pentamethylcyclopentadienyl)iridium(iii) complexes of the type [(η5-C5Me5)Ir(Aa)(dppz)]n+ (dppz = dipyrido[3,2-a:2′,3′-c]phenazine, n = 1–3), with S-coordinated amino acids (Aa) or peptides
作者:Diran Herebian、William S. Sheldrick
DOI:10.1039/b107656f
日期:2002.3.8
The DNA binding of cationic complexes of the type [(η5-C5Me5)Ir(Aa)(dppz)](CF3SO3)n (dppz = dipyrido[3,2-a:2â²,3â²-c]phenazine; n
= 1, Aa = AccysOH 7; n
= 2, Aa = AcmetOMe 4, H2cysOMe 8; n
= 3, Aa = H2metOMe 5) containing S-coordinated amino acids (HmetOH = methionine, HcysOH = cysteine) has been studied by UV-vis titration, 2D-NOESY and gel electrophoresis. The observed steady decrease in absorbance at maxima between 350 and 400 nm on UV-vis titration with CT DNA and the bathochromic shifts of these absorption maxima are consistent with stable intercalative DNA binding for these complexes. An increase
in the binding constant Kb from 8.80(6) à 104 for the monocation of 7 through 2.30(4) à 105 and 7.04(5) à 105 for the dications of 8 and 4 to 2.62(3) à 106 Mâ1 for the 3+ cation of 5 clearly reflects the strengthening of the electrostatic interaction with the negatively charged phosphodiester backbone of DNA with increasing cation charge. Analogous values of 2.81(7) à 105 and 1.26(5) à 106 Mâ1 were obtained for the (η5-C5Me5)RhIII complexes 14 (n
= 2, Aa = H2cysOMe) and 13 (n
= 3, Aa =
H2metOMe). Binding site sizes for the organometallic IrIII and RhIII complexes on CT DNA lie in the range 1.5â2.1 base pairs. NOE cross peaks for the 1 â¶ 1 complex formed between 5 and d(GTCGAC)2 are consistent with intercalation adjacent to T2 from the major groove. Complexes 4, 5 and [(η5-C5Me5)Ir(HglyglymetOH)(dppz)](CF3SO3)26 (HglyOH = glycine) cleave the supercoiled plasmid pBluescript II KS+, on irradiation for 30â180 s with a high pressure Hg lamp, to afford nicked circular and linear DNA forms. X-Ray structural analyses are reported for [(η5-C5Me5)IrCl(dppz)](CF3SO3) 3
and [(η5-C5Me5)Ir(9-Etgua)(phen)] (CF3SO3)216 (9-Etgua = 9-ethylguanine).
研究了含有S-配位氨基酸的阳离子复合物[(η5-C5Me5)Ir(Aa)(dppz)](CF3SO3)n(dppz = 二吡啶[3,2-a:2′,3′-c]酚噻唑;n = 1,Aa = AccysOH 7;n = 2,Aa = AcmetOMe 4,H2cysOMe 8;n = 3,Aa = H2metOMe 5)对DNA的结合。通过紫外-可见光滴定、二维核磁共振谱(NOESY)和凝胶电泳研究了其与CT DNA的相互作用。紫外-可见光滴定中,在350至400 nm之间的吸光度稳步下降,以及这些吸收峰的红移,与这些复合物的稳定插入性DNA结合一致。结合常数Kb从7的单阳离子8.80(6) × 10^4,通过8和4的双阳离子2.30(4) × 10^5和7.04(5) × 10^5增加到5的三阳离子2.62(3) × 10^6 M^−1,清楚地反映了随着阳离子电荷增加,与DNA的负电荷磷酸二酯主链的静电相互作用增强。对于(η5-C5Me5)RhIII复合物14(n = 2,Aa = H2cysOMe)和13(n = 3,Aa = H2metOMe),获得了类似的数值2.81(7) × 10^5和1.26(5) × 10^6 M^−1。有机金属IrIII和RhIII复合物在CT DNA上的结合位点大小在1.5–2.1个碱基对的范围内。5与d(GTCGAC)2形成的1:1复合物的NOE交叉峰与插入靠近大沟的T2一致。复合物4、5和[(η5-C5Me5)Ir(HglyglymetOH)(dppz)](CF3SO3)26(HglyOH = 甘氨酸)在高压汞灯照射30–180秒后,可对超螺旋质粒pBluescript II KS+进行切割,产生缺口环状和线性DNA形式。报告了[(η5-C5Me5)IrCl(dppz)](CF3SO3)3和[(η5-C5Me5)Ir(9-Etgua)(phen)](CF3SO3)216(9-Etgua = 9-乙基鸟嘌呤)的X射线结构分析。