A study of the molecular sources of nonideal osmotic pressure of bovine serum albumin solutions as a function of pH

K. M. Kanal, G. D. Fullerton, I. L. Cameron

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

The nonideal osmotic pressure of bovine serum albumin (BSA) solutions was studied extensively by Scatchard and colleagues. The extent of pH- and salt-dependent nonideality changes are large and unexplained. In 1992, Fullerton et al. derived new empirical expressions to describe solution nonideal colligative properties including osmotic pressure (Fullerton et al. 1992. Biochem. Cell Biol. 70:1325–1331). These expressions are based on the concepts of volume occupancy and hydration force. Nonideality is accurately described by a solute/solvent interaction parameter I and an "effective" osmotic molecular weight Ae. This paper uses the interaction-corrected nonideal expressions for osmotic pressure to calculate the hydration I values and "effective" osmotic molecular weight of BSA, Ae, as a function of pH. Both factors vary in a predictable manner due to denaturing of the BSA molecule. Both contribute to an increase in osmotic pressure for the same protein concentration as the solution pH moves away from the isoelectric point. Increased nonideality is caused by larger hydration resulting from larger solvent-accessible surface areas and by the decrease in "effective" osmotic molecular weight, Ae, due to segmental motion of denatured (filamentous) molecules.

Original languageEnglish (US)
Pages (from-to)153-160
Number of pages8
JournalBiophysical Journal
Volume66
Issue number1
DOIs
StatePublished - 1994
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics

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