TY - JOUR
T1 - Stability of proteins in the presence of carbohydrates; experiments and modeling using scaled particle theory
AU - O'Connor, Thomas F.
AU - Debenedetti, Pablo G.
AU - Carbeck, Jeffrey D.
N1 - Funding Information:
P.G.D. gratefully acknowledges the support of the Department of Energy, Division of Chemical Sciences, Geosciences and Biosciences, Office of Basic Energy Sciences, Grant No. DE-FG02-87ER13714, and of the National Science Foundation through Collaborative Research in Chemistry Grant No. CHE 0404699.
PY - 2007/4
Y1 - 2007/4
N2 - 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.
AB - 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.
KW - Capillary electrophoresis
KW - Carbohydrate
KW - Preferential interactions
KW - Protein stability
KW - Scaled particle theory
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U2 - 10.1016/j.bpc.2006.12.004
DO - 10.1016/j.bpc.2006.12.004
M3 - Article
C2 - 17234323
AN - SCOPUS:33847184181
SN - 0301-4622
VL - 127
SP - 51
EP - 63
JO - Biophysical Chemistry
JF - Biophysical Chemistry
IS - 1-2
ER -