Thermodynamics of binding of D-galactose and deoxy derivatives thereof to the L-arabinose-binding protein |
| |
Authors: | Daranas Antonio Hernandez Shimizu Hiroki Homans Steve W |
| |
Institution: | Astbury Centre for Structural Molecular Biology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. |
| |
Abstract: | 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 DeltaG degrees (int) at 308 K for the 1-, 2-, 3-, and 6-hydroxyl groups of galactose is remarkably constant (approximately -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 (approximately 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. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|