Formation of Porphyrin-metal Complex Catalyzed by Single Strand DNA

在本研究中，通过对卟啉-DNA相互作用的结构研究，阐明了单链DNA是否有可能折叠，从而为不与核酸天然结合的阴离子卟啉创建特定的结合口袋。在PS5.ST1(DTCGTGGGTCATTGGGGGGGGTGGTGGGTGGTGGTGGGTGGTGGCTGGTCC)和其他富含G的低聚物存在和不存在的情况下，HPLC首次研究了进入MPIX的情况，结果与以前报道的结果几乎相同(3)CD光谱已被用于区分平行和反平行G-四链(4，5)，前四链在260 nm附近显示正CD带，在240 nm处显示负CD带。后四链在290 nm附近有一个正的CD带，在265 nm处有一个较弱的负带。在无K~(++)离子和K~(++)离子存在的条件下，对PS5.ST-1(25微米)进行了不同温度下的圆二色谱研究。在没有K~(++)的情况下，样品在0ﾟC出现了2 6 5和2 85 nm两个正峰，而随着温度的升高，2 6 5 nm峰消失，2 85 nm峰减弱。在0-80ﾟC温度范围内，当K~+离子存在时，PS5.ST1的CD光谱也随温度变化。两个正峰都出现在25ﾟC以下，且在265 nm处的峰强度比不存在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仍具有有序结构，K~(++)离子的加入诱导了平行G-四链体的成分。亚米诺质子信号是对称性和化学计量的指示器。核磁共振谱显示峰的化学位移发生了一些变化，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.ST 1 (25 muM) 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ﾟC, 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.ST1 in the presence of K^+ ion in the temperature range of 0-80ﾟC.Both the positive peaks appeared below 25ﾟC, 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.ST1 takes an ordered structure, and that the addition of K^+ ion induces components of parallel G-quadruplexes.^1HNMR measurements were carried out for PS5.ST1 in the absence and presence of K^+ ion. The imino proton 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.