Accessing the kinetics of the supra-tauc range via relaxation dispersion NMR spectroscopy

by David Ban
Doctoral thesis
Date of Examination:2013-08-12
Date of issue:2013-10-30
Advisor:Prof. Dr. Christian Griesinger
Referee:Prof. Dr. Bert de Groot
Referee:Prof. Dr. Kai Tittmann
Persistent Address: http://dx.doi.org/10.53846/goediss-4029

 

 

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Abstract

English

Nuclear Magnetic Resonance spectroscopy (NMR) is capable of attaining dynamic information of motions over a broad range of time scales under physiological relevant conditions while maintaining atomic resolution. Of the NMR accessible time scales structural information from the supra-tauc range, a four orders of magnitude time window between the overall rotational correlation time to the relaxation dispersion limit of 40 microseconds has been accessed only via structural information derived from residual dipolar couplings. Previously for ubiquitin, motion from the supra-tauc range could be linked to its molecular recognition process. Here, kinetics displayed within this regime are measured for the protein ubiquitin and can be attributed to the lifetime of interconversion between conformers for ubiquitin free in solution. This is demonstrated by super-cooled relaxation dispersion (RD) type experiments. It is also shown that the accessible time window for RD type experiments can be increased with the use of a cryogenically cooled probehead. For 15N, 13C, and 1H nuclei motions as fast as 25, 10, and 4 microseconds are now possible. This technique was further applied to measure RD for a variety of nuclei across ubiquitin. The extended time resolution for 15N nuclei was also applied to enhance the accuracy of kinetics measured by other RD experiments. Additionally, preliminary work is presented on the detection of conformational sampling events during a binding interaction between two proteins. As it becomes increasingly transparent that the dynamics of a system can govern its function, the approaches outlined here can help in validating, testing, or reinforcing our understanding of the complex and dynamic nature of systems of biological interest.
Keywords: NMR spectroscopy; Relaxation Dispersion; Protein Dynamics; ubiquitin; supra tau-c
 
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