Thermodynamic characterizations of coulombic end effects and coupled folding effects on binding of cationic oligopeptides to nucleic acids. Two-domain of preferential solute-protein interactions

The research presented here addresses important questions about thermodynamic effects of salt-nucleic acid interactions on ligand-DNA binding and effects of solute-protein interactions on protein stability. Model systems are used to investigate the thermodynamic basis of two major coupled processes in protein-nucleic acid interactions: counterion release due to the reduction of DNA charge density and coupled folding of the protein binding site upon complexation.;We demonstrate the central importance of the polyelectrolyte character of DNA by quantifying the large differences in the binding constant ;We investigate effects of coulombic interactions and coupled folding on the binding of four extended helical and nonhelical tetravalent ;To understand the thermodynamic consequences of solute-protein interactions, we investigate interactions of bovine serum albumin (BSA) with two smaller solutes (glycine betaine and urea) in aqueous solution. Solute-BSA preferential interactions and the hydration of BSA are analyzed in terms of a general two-domain (local, bulk) model. Glycine betaine is found to be completely excluded from the first layer of hydration water surrounding BSA. Urea is found to be weakly accumulated near BSA; the extent of accumulation is proportional to urea concentration and interpretable as a weak binding interaction with polar protein surface areas.