Probing miniprotein stability via backbone thioester exchange

ORGN 257

Samuel H. Gellman, Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, WI 53706
Understanding the forces that control protein folding patterns remains a topic of widespread interest. Protein folding thermodynamics are generally studied via structure disruption with either heat or a chemical denaturant. Results obtained under partially denaturing conditions are extrapolated to native conditions in order to determine how changes in sequence are correlated with changes in stability. A concern with this approach is that the folded and unfolded states may differ between conditions under which the data are obtained and native conditions. We have developed a technique to study protein conformational stability under native conditions. A backbone amide group is replaced with a structurally analogous thioester group, and thiol-thioester exchange equilibria are then used to gain the desired information. Applications to small folding motifs will be discussed.