Stability of proteins in the presence of carbohydrates; experiments and modeling using scaled particle theory

Thomas F. O'Connor, Pablo G. Debenedetti, Jeffrey D. Carbeck

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


The effects of sucrose and fructose on the free energy of unfolding, ΔGN → D, and on the change in hydrodynamic radius, RH, upon unfolding were measured for RNase A and α-lactalbumin. Recently we analyzed the results for RNase A and showed that the effects of the carbohydrates on the protein's thermal stability can be accurately accounted for by scaled particle theory (SPT), and are thus largely entropic in nature. In this paper we extend this analysis to α-lactalbumin and demonstrate the generality of this finding. We also investigate the relationship between SPT and the thermodynamic formalism of preferential interactions. The preferential binding parameters calculated using SPT are in excellent agreement with experimentally measured values available in the literature. This agreement is expected to hold as long as enthalpic interactions between the cosolute and the protein are not important, as appears to be the case here. Finally we use the experimental data and SPT to calculate the change in the number of sugar molecules excluded from the protein surface during unfolding from knowledge of the preferential binding parameter for the native and denatured state of the protein.

Original languageEnglish (US)
Pages (from-to)51-63
Number of pages13
JournalBiophysical Chemistry
Issue number1-2
StatePublished - Apr 2007

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Organic Chemistry


  • Capillary electrophoresis
  • Carbohydrate
  • Preferential interactions
  • Protein stability
  • Scaled particle theory


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