| An approximation method of considering J-coupling effects on chemical exchange saturation transfer (CEST) NMR experiments and the studies on folding of two proteins by CEST methods are presented in the thesis. The J-coupling approximation method was constructed upon a theoretical derivation, examined by simulations and supported by 13CO and 15N CEST experiments on meACP, a protein undergoing a folding/unfolding exchange process. Furthermore, CEST experiments on meACP folding demonstrated a partially unfolded intermediate state, whose N-terminal region is unfolded while the C-terminal region is folded, as well as a native-like transition state. Finally, CEST and relaxation dispersion experiments on the repetitive domain from minor ampullate spider silk protein (RPmi) showed that there exists a fast exchange process (~3900 s-1) between the native state and possibly an unfolded state in the system. Overall, the thesis demonstrates an improvement of CEST methods by considering J-coupling effects and CEST applications in studying protein folding, the mechanism of which remains missing. |
