Shape dependence of the radial distribution function of hydration water around proteins

Abstract

The characterization of hydration water in proteins is important to understand their structure, function and folding properties. A calculation of the shape parameters reveals considerable asymmetry in the shapes of globular proteins. The present study suggests a generalized approach for the calculation of radial distribution of hydration water by accounting for the shape asymmetry in proteins. The surface and radial distribution function is analyzed for three groups of high resolution globular proteins and nonglobular proteins. This generalized approach depicts a considerable difference in the hydration water distribution pattern around aspherical proteins as compared to the earlier method and this difference is more pronounced for nonglobular proteins. The peaks for normalized RDF are found to be sharper compared to those of bulk water. The normalized RDF of hydration water exactly coincides with that of the bulk beyond 8.0 Å. The radial distribution of hydration water as a function of the water–protein distance matches with the experimentally observed distribution of hydration water around myoglobin. The results reveal that the distribution of hydration water is dependent on the shapes of proteins and hence a generalized approach should be used for the calculation of hydration water distribution around proteins, especially for nonglobular proteins.