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首页> 外文期刊>Chemistry: A European journal >Photooxidation of guanine by a ruthenium dipyridophenazine complex intercalated in a double-stranded polynucleotide monitored directly by picosecond visible and infrared transient absorption spectroscopy
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Photooxidation of guanine by a ruthenium dipyridophenazine complex intercalated in a double-stranded polynucleotide monitored directly by picosecond visible and infrared transient absorption spectroscopy

机译：皮秒秒可见光和红外瞬态吸收光谱法直接监测插在双链多核苷酸中的钌二吡啶吩嗪络合物对鸟嘌呤的光氧化作用

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摘要

Transient species formed by photoexcitation (400 nm) of [Ru(dppz)(tap)(2)](2+) (1) (dppz = dipyrido[3,2-a:2',3'-c]phenazine; tap = 1,4,5,8-tetraazaphenanthrene) in aqueous solution and when intercalated into a double-stranded synthetic polynucleotide, [poly(dG-dC)](2), have been observed on a picosecond timescale by both visible transient absorption (allowing monitoring of the metal complex intermediates) and transient infrared (IR) absorption spectroscopy (allowing direct study of the DNA nucleobases). By contrast with its behavior when free in aqueous solution, excitation of 1 when bound to [poly(dGdC), causes a strong increase in absorbance at 515 nm due to formation of the reduced complex [Ru(dppz)(tap)(2)](+) (rate constant = (2.0 +/- 0.2) x 10(9) s(-1)). The subsequent reformation of 1 proceeds with a rate constant of (1.1 +/- 0.2) x 10(8) s(-1). When the process is carried out in D2O, the rates of forma-tion and removal of [Ru(dppz)(tap)(2)](+) are reduced (rate constants (1.5 +/- 0.3) x 10(9) and (0.7 +/- 0.2) x 10(8) s(-1) respectively) consistent with proton-coupled electron transfer processes. Picosecond transient IR measurements in the 1540-1720 cm(-1) region in D2O solution confirm that the reduction of 1 intercalated into [poly(dG-dC)](2) is accompanied by bleaching of IR ground-state bands of guanine (1690 cm(-1)) and cytosine (1656 cm(-1)), each with similar rate constants.
机译：通过[Ru（dppz）（tap）（2）]（2+）（1）的光激发（400 nm）形成的瞬态物种（dppz =双吡啶[3,2-a：2'，3'-c]吩嗪; = 1,4,5,8-四氮杂菲）在水溶液中插入到双链合成多核苷酸[poly（dG-dC）]（2）中时，通过可见的瞬时吸收在皮秒级的时间范围内观察到（允许监测金属络合物中间体）和瞬态红外（IR）吸收光谱（允许直接研究DNA核碱基）。与在水溶液中游离时的行为相反，与[poly（dGdC）结合时激发为1，会由于形成还原的复合物[Ru（dppz）（tap）（2）而在515 nm处引起吸光度的强烈增加。 ]（+）（速率常数=（2.0 +/- 0.2）x 10（9）s（-1））。随后的1的重整以（1.1 +/- 0.2）x 10（8）s（-1）的速率常数进行。在D2O中进行处理时，[Ru（dppz）（tap）（2）]（+）的形成和去除速率降低（速率常数（1.5 +/- 0.3）x 10（9）和（0.7 +/- 0.2）x 10（8）s（-1）分别与质子耦合电子转移过程一致。在D2O溶液中1540-1720 cm（-1）区域进行皮秒瞬态IR测量，证实插入[poly（dG-dC）]（2）的1的减少伴随着鸟嘌呤的IR基态能带的脱色（ 1690 cm（-1））和胞嘧啶（1656 cm（-1）），每个都具有相似的速率常数。

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