Quantitative analysis of backbone motion in proteins using MAS solid-state NMR spectroscopy

Abstract

We present a comprehensive analysis of protein dynamics for a micro-crystallin protein in the solid-state. Experimental data include 15N T1 relaxation times measured at two different magnetic fields as well as 1H-15N dipole, 15N CSA cross correlated relaxation rates which are sensitive to the spectral density function J (0) and are thus a measure of T2 in the solid-state. In addition, global order parameters are included from a 1H,15N dipolar recoupling experiment. The data are analyzed within the framework of the extended model-free Clore-Lipari-Szabo theory. We find slow motional correlation times in the range of 5 and 150 ns. Assuming a wobbling in a cone motion, the amplitude of motion of the respective amide moiety is on the order of 10° for the half-opening angle of the cone in most of the cases. The experiments are demonstrated using a perdeuterated sample of the chicken α-spectrin SH3 domain. © Springer Science+Business Media B.V. 2009.