Thermodynamics of Binding of d-Galactose and Deoxy Derivatives thereof to the l-Arabinose-binding Protein

We report the thermodynamics of binding of d-galactose and deoxy derivatives thereof to the arabinose binding protein (ABP). The “intrinsic” (solute−solute) free energy of binding ΔG°int at 308 K for the 1-, 2-, 3-, and 6-hydroxyl groups of galactose is remarkably constant (∼−30 kJ/mol), despite the fact that each hydroxyl group subtends different numbers of hydrogen bonds in the complex. The substantially unfavorable enthalpy of binding (∼30 kJ/mol) of 1-deoxygalactose, 2-deoxygalactose, and 3-deoxygalactose in comparison with galactose, cannot be readily accounted for by differences in solvation, suggesting that solute−solute hydrogen bonds are enthalpically significantly more favorable than solute−solvent hydrogen bonds. In contrast, the substantially higher affinity for 2-deoxygalactose in comparison with either 1-deoxygalactose or 3-deoxygalactose derives from differences in the solvation free energies of the free ligands.

Bibliographic Details

Main Authors:	Hernández Daranas, Antonio, Shimizu, Hiroki, Homans, Steve W.
Other Authors:	Biotechnology and Biological Sciences Research Council (UK)
Format:	artículo biblioteca
Language:	English
Published:	American Chemical Society 2004-09-01
Subjects:	Free energy, Ligands, Solvation, Thermodynamics, Noncovalent interactions,
Online Access:	http://hdl.handle.net/10261/213406 http://dx.doi.org/10.13039/501100000268
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