Conformational Fluctuations of Hen Lysozyme Investigated by High Pressure NMR Spectroscopy

High-resolution high pressure NMR is a novel method for detecting site-specific conformational fluctuation in proteins. Six residues in the s domain and at the α/s domain interface of hen lysozyme showed anomalously large and non-linear 15N and 1H chemical shift changes with pressure, suggesting preferential conformational fluctuations within the folded manifold. All these residues lie close to water-containing cavities. Temperature-induced structural changes at a pressure 2000 bar between 30 and —20 °C have also been studied. The residues disappearing at low temperature also lie close to water-containing cavities, indicating that the slow conformational fluctuations are likely to be correlated with water penetration into cavities. All these results suggest that both the rapid and slow conformational fluctuations of hen lysozyme are closely related to the dynamics of cavities and hydration.