Myoglobin in crowded solutions: structure and diffusion

We present a neutron scattering study of the structure and diffusion of myoglobin solutions at high concentration. The protein-protein structure factor was determined by small angle neutron scattering (SANS) measurements using mean spherical analysis (MSA), and the intermediate scattering function was measured by neutron spin-scho spectroscopy. We observe the cross-over between self-diffusion at high Q and collective diffusion below the structure factor maximum. The self-diffusion coefficient decreases exponentially with concentration. The collective diffusion coefficient is shown to increase at low Q due to direct interactions. (C) 2003 Elsevier Science B.V. All rights reserved.