Distribution of the second virial coefficients of globular proteins

TL;DR

This paper models the distribution of second virial coefficients in globular proteins, showing that their values are narrowly distributed and Gaussian-shaped due to surface patch contributions, aligning with experimental observations.

Contribution

It introduces a simple probabilistic model of globular proteins that explains the narrow Gaussian distribution of their second virial coefficients at crystallization conditions.

Findings

Second virial coefficients are narrowly distributed around a mean value.

The distribution of these coefficients is Gaussian due to surface patch contributions.

The model reproduces the experimentally observed narrow range of values.

Abstract

George and Wilson [Acta. Cryst. D 50, 361 (1994)] looked at the distribution of values of the second virial coefficient of globular proteins, under the conditions at which they crystallise. They found the values to lie within a fairly narrow range. We have defined a simple model of a generic globular protein. We then generate a set of proteins by picking values for the parameters of the model from a probability distribution. At fixed solubility, this set of proteins is found to have values of the second virial coefficient that fall within a fairly narrow range. The shape of the probability distribution of the second virial coefficient is Gaussian because the second virial coefficient is a sum of contributions from different patches on the protein surface.