Measurement of N15 - T1 relaxation rates in a perdeuterated protein by magic angle spinning solid-state nuclear magnetic resonance spectroscopy

In this paper, we present the measurement of N15 - T1 relaxation times in the solid state for a perdeuterated protein for which exchangeable protons are back substituted during recrystallization using a buffer which contains 10% H2 O and 90% D2 O. We find large variations of the N15 relaxation time, even within the same Β sheet. By comparing N15 - T1 relaxation times measured for a protonated and a deuterated protein (using the above mentioned approach), we conclude that H1 driven N15, N15 spin diffusion has a significant impact on the absolute N15 relaxation time in protonated proteins. This effect is important for a quantitative analysis of relaxation data in terms of molecular dynamics.