Adsorption heterogeneity and thermodynamic driving forces in anion exchange equilibria of cytochrome b5

Davinder S. Gill, David J. Roush, Richard C. Willson

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Batch adsorption studies of recombinant soluble core of rat cytochrome b5 on the polymeric strong anion exchanger, Mono Q, show non-Langmuirian adsorption isotherms. Adsorption data are well fit by the Hill equation. Concave-upward Scatchard plots, and values of the Hill coefficient below unity, imply heterogeneous adsorption due to negative lateral interaction between adsorbed molecules and/or nonuniform binding affinities of adsorbent sites. Adsorption isotherms from the batch studies can be interpreted in terms of a stoichiometric displacement model for obtaining the apparent number of binding interactions (Z) between the protein and the adsorbent surface. Z values obtained are low and fractional and represent an average over diverse binding forms arising from surface heterogeneity, van't Hoff plots of the adsorption data vary in slope over the experimental temperature range. The positive enthalpies at low temperatures indicate a dominant entropic contribution to the driving force, possibly arising from the liberation of bound ions and waters of solvation upon adsorption.

Original languageEnglish (US)
Pages (from-to)1-7
Number of pages7
JournalJournal of Colloid And Interface Science
Volume167
Issue number1
DOIs
StatePublished - Oct 1 1994

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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