Mémoire, Partim B

Abstract

Nuclear Magnetic Resonance (NMR) relaxation experiments can provide major insights into the study of protein dynamics. Over the years, various experiments have been developed to measure the dynamic phenomena that animate proteins. Relaxation experiments such as R1, R2 and hNOE provide information on fast dynamics occurring at the picosecond to the nanosecond timescale. Other experiments like Relaxation Dispersion R2 (RD R2) allow to measure dynamics at an intermediate timescale, from the microsecond to the millisecond. Finally, the Chemical Exchange Saturation Transfer (CEST) experiments give access to slow dynamics occurring at the millisecond to the second. The complementarity of these experiments allows to gain a general view of the dynamic phenomena of proteins. To explore the importance of these experiments, the dynamics of three proteins of different sizes have been studied through the aforementioned relaxation experiments. The smallest protein studied is the Cold Shock Protein mesophile or CSPm (7 kDa), a class of proteins produced by bacteria when they are submitted to sudden temperature drops. The second protein investigated is TEM-1 (29.7 kDa), a beta-lactamase responsible for the resistance to antibiotics. Finally, a complex of TEM-1 bound to a nanobody (TEM-1_Nb), which drastically increases the size of the protein to 45 kDa, will be studied. Performing various NMR relaxation experiments on these samples reveals the potential of these experiments for the measure and characterization of the dynamics that animate proteins.