Abstract
Interactions governing protein folding, stability, recognition, and activity are mediated by hydration. Here, we use small-angle neutron scattering coupled with osmotic stress to investigate the hydration of two proteins, lysozyme and guanylate kinase (GK), in the presence of solutes. By taking advantage of the neutron contrast variation that occurs upon addition of these solutes, the number of protein-associated (solute-excluded) water molecules can be estimated from changes in both the zeroangle scattering intensity and the radius of gyration. Poly(ethylene glycol) exclusion varies with molecular weight. This sensitivity can be exploited to probe structural features such as the large internal GK cavity. For GK, small-angle neutron scattering is complemented by isothermal titration calorimetry with osmotic stress to also measure hydration changes accompanying ligand binding. These results provide a framework for studying other biomolecular systems and assemblies using neutron scattering together with osmotic stress.
Original language | English |
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Pages (from-to) | 2777-2789 |
Number of pages | 13 |
Journal | Biophysical Journal |
Volume | 94 |
Issue number | 7 |
DOIs | |
State | Published - Apr 2008 |
Funding
This research was supported by the National Research Council, the National Science Foundation under Agreement No. DMR-0454672 (NCNR), and the Intramural Research Program of the National Institute of Child Health and Human Development and National Institutes of Health.