Unfolding Kinetics of G-quadruplexes by NMR

• Main Authors: Ming-Hao Li, 李明浩
• Other Authors: Ta-Chau Chang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/00225959146340114978

碩士 === 國立陽明大學 === 生醫光電研究所 === 101 === The study of folding and unfolding kinetics of human telomeric G-quadruplex (G4) structures is important for biomedical research and material design. Of interest is that that slight variations of human telomeric sequences can form different types of G4 structures. It is important to examine whether there is a correlation between thermal stability and unfolding kinetics of these G4 structures. Hence, we measured the melting temperature (Tm) and determined the Gibbs free energy (∆G) based on the differential scanning calorimetry (DSC) of each G4 structures. Both of them showed slight structure-dependence, except the Tm of parallel G4 structure is ~10 oC higher than that of nonparallel G4 structure. We further used imino proton NMR spectra to monitor unfolding kinetics of these telomeric G4 structures as a function of time based on hybridization DNA and hydrogen-deuterium exchange (HDX) experiments. The hybridization results showed that the decay times of different imino proton signals for each telomeric G4 structure are quite similar, which are also consistent with the decay time of rate-determining step obtained from HDX measurements. It is suggested that the unfolding process of G4 structure is not a step-by-step sequential process, but a randomly global unfolding. The key finding is that the unfolding times of these G4 structures are quite different and shows no correlation between thermal stability and unfolding kinetics. Considering the dynamic system of physiological condition, kinetics might be more relevant for the study of G4 structures in biological system.