Proton Exchange Coupled to the Specific Binding of Alkylsulfonates to Serum Albumins.
From: Department of Life Sciences and Chemistry, Roskilde University, PO Box 260, 1 Universitetsvej, DK-4000, Roskilde, Denmark.
Biochimica et biophysica acta
- Publish Date: Jul 2006
- ISSN: 0006-3002
- Volume: 1764
- Issue: 7
- Pages: 1243-51
- Medium: Print
- Language: English
- Citation (JAMA): Lund Henrik, Christensen Bitten Plesner, Nielsen Anders Dybdal, et al. Proton Exchange Coupled to the Specific Binding of Alkylsulfonates to Serum Albumins.. Biochim. Biophys. Acta Jul 2006;1764:1243-51
Abstract
We have applied isothermal titration calorimetry to investigate the linkage between ligand binding and the uptake or release of protons by human serum albumin (HSA) and bovine serum albumin (BSA). The ligands were sodium decyl sulfate (SDeS) and sodium dodecyl sulfate (SDS). Within a certain temperature range, the binding isotherm could be clearly resolved into two classes of sites (high affinity and low affinity) and modeled assuming independence and thermodynamic equivalence of the sites within each class. Measurements at pH 7.0 in different buffer systems revealed that the binding of SDS to the high affinity sites did not couple to any exchange of protons in either of the proteins. Saturation of the 6-8 low affinity sites for SDS, on the other hand, brought about the release of two protons from both HSA and BSA. In addition to elucidating the pH dependence of ligand binding, this analysis stressed that binding enthalpies for the low affinity sites measured by calorimetry must be corrected for effects due to the concomitant protonation of the buffer. The shorter ligand SDeS bound to HSA with a comparable stoichiometry but with four times lower affinity. Interestingly, no proton linkage was observed for the binding of SDeS. An empirical structural analysis suggested that His 242 in site 7 (of HSA) is a likely candidate for one of the proton donors.
Mesh Headings (Keywords): Algorithms, Alkanesulfonates, Animals, Binding Sites, Buffers, Calorimetry, Cattle, Humans, Protein Binding, Protons, Serum Albumin, Sodium Dodecyl Sulfate, Temperature, Thermodynamics
Check for Full Text / PubMed Unique Identifier (PMID): 16831575
This abstract is part of PubMed, a service of the U.S. National Library of Medicine. PubMed includes more than 17 million citations from MEDLINE and other life science journals for biomedical articles. See Copyright and Disclaimers.
Linked medical terms appearing on this page are added by Healia to help readers find more information and are not part of the original PubMed document.
The data herein was last updated on July 8th, 2008 and may not reflect the most current and accurate data available from NLM.