Mechanistic study for porpyrin metallation occurring in DNA-quartet structure

本研究对卟啉- dna相互作用进行了结构研究，以阐明单链dna是否有可能折叠为阴离子卟啉创造特异性的结合口袋，而阴离子卟啉不能自然地与核酸结合。在PS5存在和不存在的情况下，首次研究了Cu^<2+>金属化成MPIX的动力学。ST1 （dtcgtgggtcattgtgggtgggtgtgtggctggtcc）等富g低聚物。结果与先前报道的几乎相同(3)。CD光谱已被用于区分平行和反平行的g -四聚体（4,5），前四聚体在约260 nm处表现出正CD带，在240 nm处表现出负CD带。后一种四聚体在290 nm处呈现出正CD带，在265 nm处呈现出较弱的负CD带。对PS5进行了CD光谱分析。ST1 （25 μM）在不存在K^+离子和不存在K^+离子的情况下，在不同温度下。在没有K^+的情况下，样品在0℃时在265和285 nm处有两个正峰，而随着温度的升高，265 nm处的一个正峰消失，285 nm处的一个正峰下降。对PS5也进行了温度相关的CD光谱分析。在0 ~ 80℃的温度范围内，存在K^+离子的st1。在25℃以下均出现了正峰，且265 nm处的峰强度比没有K^+离子时强得多。这些结果表明，即使在没有K +离子的情况下，PS5。st1采用有序结构，K^+离子的加入诱导出平行g -四重复合物的组分。^对PS5进行了1H核磁共振测量。在没有和存在K^+离子时的st1。亚质子信号是对称和化学计量的标志。核磁共振谱显示出峰的化学位移有一定的变化，这可能与CD谱的变化相对应。

In this study, the structural study on porphyrin-DNA interactions was performed in order to clarify whether it is possible for single-stranded DNAs to fold to create specific binding pockets for anionic porphyrins, which do not naturally bind to nucleic acids.The kinetics of the metallation of Cu^<2+> into MPIX was first examined in the presence and absence of PS5. ST1 (dTCGTGGGTCATTGTGGGTGGGTGTGGCTGGTCC) and other G-rich oligomers by HPLC.The results were almost identical to that as previously reported (3).CD spectroscopy has been used to distinguish between parallel and antiparallel G-quadruplexes (4, 5) The former quadruplexes exhibit a positive CD band around 260 nm and a negative CD band at 240 nm. The latter quadruplexes exhibit a positive CD band around 290 nm and a weaker negative band at 265 nm. CD spectroscopy was carried out for PS5. ST1 (25 μM) at various temperatures in the absence and presence of K^+ ion. In the absence of K^+, this sample showed two positive peaks at 265 and 285 nm at 0 ℃, while at increasing temperatures, one at 265 nm disappeared, and the other at 285 nm decreased. Temperature-dependent CD spectroscopy was also performed for PS5. ST 1 in the presence of K^+ ion in the temperature range of 0-80 ℃. Both the positive peaks appeared below 25 ℃, and the intensity of the peak at 265 nm was much stronger than that in the absence of K^+ ion. These results indicate that even in the absence of K^+ ion, PS5. ST 1 takes an ordered structure, and that the addition of K^+ ion induces components of parallel G-quadruplexes.^1H NMR measurements were carried out for PS5. ST 1 in the absence and presence of K^+ ion. The iminoproton signals are an indicator of symmetry and stoichiometry. The NMR spectra show some change in the chemical shifts of the peaks, which may correspond with the change in the CD spectra.