On the solubility of proteins as a function of pH: Mathematical development and application

Author(s)

Mercier Franco, Luis Fernando ^[1] ; Pessoa Filho, Pedro de Alcantara ^[1]

Affiliation

^[1] Univ Sao Paulo, Biochem Engn Lab, Dept Chem Engn, Sch Engn, BR-05424970 Sao Paulo - Brazil

• Document type: Journal article
• Source: Fluid Phase Equilibria; v. 306, n. 2, p. 242-250, JUL 25 2011.
• Web of Science Citations: 8

Abstract

Thermodynamic relations between the solubility of a protein and the solution pH are presented in this work. The hypotheses behind the development are that the protein chemical potential in liquid phase can be described by Henry's law and that the solid-liquid equilibrium is established only between neutral molecules. The mathematical development results in an analytical expression of the solubility curve, as a function of the ionization equilibrium constants, the pH and the solubility at the isoelectric point. It is shown that the same equation can be obtained either by directly calculating the fraction of neutral protein molecules or by integrating the curve of the protein average charge. The methodology was successfully applied to the description of the solubility of porcine insulin as a function of pH at three different temperatures and of bovine beta-lactoglobulin at four different ionic strengths. (C) 2011 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 09/06575-0 - Thermodynamic modeling of solid-liquid equilibrium in protein aqueous systems: effect of pH
• Grantee: Luís Fernando Mercier Franco
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 08/11232-1 - Study on the influence of co-solvents on thermodynamic properties of proteins in solution
• Grantee: Pedro de Alcântara Pessôa Filho
• Support Opportunities: Regular Research Grants