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采用电喷雾质谱(ESI-MS)和圆二色谱(CD)法研究了Kras基因G-四链体的形成与性质,结果表明,在阳离子条件下,KS1序列形成的是平行构象为主的混合构象G-四链体。实验探索了不同位置G碱基突变对Kras原生型序列G-四链体结构的影响,发现在KS1序列中,第6位G碱基突变对G-四链体影响不大;第13位G碱基突变会导致G-四链体层数减少;而第18、19位G碱基突变会导致G-四链体稳定性下降,同时G-四链体构象也向反平行移动,说明这些位置的G碱基对KS1序列G-四链体的形成有较大的贡献,它们很有可能参与了G-四分体平面的组成,最终形成了特殊的G-四链体结构。虽然不同位置的碱基突变对KS1序列G-四链体的影响各不相同,但突变后的序列形成G-四链体的能力整体比原生型序列弱,这在一定程度上表明,生物体内一部分基因突变后所导致的癌症可能与G-四链体结构的破坏有关。该结果可为G-四链体的结构和生物学功能研究提供更多信息,同时也可为相关抗癌药物的研制提供更广阔的思路和方向。 相似文献
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The discrimination of four pairs of cyclic peptide diastereomers were successfully achieved by ESI-MS. The ratio of ions’ abundance ratios between A and B isomers in MS/MS spectra was defined as a parameter(rA, B) for discriminating diastereomers. All the four rA, B values deviates far from 1, which demonstrates excellent discrimination of the four pairs of diastereomers. The diverse spectral behaviors of CP1-CP6 was found attributing to ‘mobile proton’ transfer diversities and steric hindrance at fragmentation sub-surrounding due to chiral differences. MSn spectra illustrate that both CP7 and CP8 fragment through bx-yz and a1-yx ring-opening mechanisms and their chiral differences result in the predilection of the two ring-opening modes. 相似文献
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For Bcl-2, VEGF, c-Myc oncogene promoter, we directly observed that the G-rich sequences preferentially adopt G-quadruplex structures by ESI-MS. And the non-covalent interaction of the G-quadruplexes and 34 small molecules was investigated. The dimeric G-quadruplex structures of HIV-1 IN inhibitors were detected by ESI-MS for the first time. We observed the specific binding of a perylene derivative, which could shift the equilibrium to the dimeric G-quadruplex, while the polyamide induced a structural change to the intramolecular one. 相似文献
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李卉卉 《徐州工程学院学报》2006,21(8):92-93
高校新生是处在高中与大学的过渡时期,有其特定的特点,了解高校新生的学风问题及加强新生的学风建设,对学生的成才有重要意义。结合本人做学生工作的一点体会,本文针对新生的学风问题及对策做了浅析。 相似文献
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