Light-scattering studies of protein solutions: Role of hydration in weak protein-protein interactions

A. Paliwal, D. Asthagiri, D. Abras, A. M. Lenhoff, M. E. Paulaitis

Research output: Contribution to journalArticlepeer-review

Abstract

We model the hydration contribution to short-range electrostatic/dispersion protein interactions embodied in the osmotic second virial coefficient, B 2, by adopting a quasi-chemical description in which water molecules associated with the protein are identified through explicit molecular dynamics simulations. These water molecules reduce the surface complementarity of highly favorable short-range interactions, and therefore can play an important role in mediating protein-protein interactions. Here we examine this quasi-chemical view of hydration by predicting the interaction part of B2 and comparing our results with those derived from light-scattering measurements of B 2 for staphylococcal nuclease, lysozyme, and chymotrypsinogen at 25°C as a function of solution pH and ionic strength. We find that short-range protein interactions are influenced by water molecules strongly associated with a relatively small fraction of the protein surface. However, the effect of these strongly associated water molecules on the surface complementarity of short-range protein interactions is significant, and must be taken into account for an accurate description of B2. We also observe remarkably similar hydration behavior for these proteins despite substantial differences in their three-dimensional structures and spatial charge distributions, suggesting a general characterization of protein hydration.

Original languageEnglish (US)
Pages (from-to)1564-1573
Number of pages10
JournalBiophysical journal
Volume89
Issue number3
DOIs
StatePublished - Sep 2005

ASJC Scopus subject areas

  • Biophysics

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