Disentangling the Coil: Modulation of Conformational and Dynamic Properties by Site-Directed Mutation in the Non-Native State of Hen Egg White Lysozyme

The conformational analysis of non-native states of proteins remains one of the most difficult problems in structural biology, because such states are represented by a superimposition of several states that are rapidly interconverting. Hence, model building of the conformational ensemble remains challenging, although many different biophysical observables can be determined in non-native states of proteins. Here, we present a comprehensive analysis of non-native states of wild-type and mutant forms of the model protein lysozyme by nuclear magnetic resonance spectroscopy. Relaxation rates, chemical shifts, backbone and side chain coupling constants, residual dipolar couplings, diffusion rate constants, and small-angle scattering data merged with computational approaches, such as <i>flexible meccano</i> and ASTEROIDS, allow the description of the non-native state of hen egg white lysozyme in unprecedented detail.