Simplified Equilibrium Model for Exploring the Combined Influences of Concentration, Aggregate Shape, Excluded Volume, and Surface Adsorption upon Aggregation Propensity and Distribution of Globular Macromolecules.

Abstract

A mesoscopic model for the equilibrium self-association of a globular macromolecule that may form oligomers of various shapes and unlimited sizes is presented. Allowance is made within this model for the effects of variation in the free energy of subunit contact within an oligomer of specified size and different shapes, the free energy of adsorption of an oligomer of specified size and shape to a planar surface, and the free energy of nonspecific excluded volume interaction between an oligomer of specified size and shape and an inert species occupying a specified fraction of total volume. The model is analytically soluble and permits rapid calculation and analysis of the effects of variation in each of the three free energy parameters upon the concentration dependence of the weight-average stoichiometry of the oligomer, the fraction of total macromolecule that is adsorbed, and the fraction of differently shaped oligomers that are adsorbed and in free solution.