Mass spectrometry and NMR analysis of ligand binding by human liver fatty acid binding protein

Abstract

Protein-ligand interactions are driven by many factors, including protein conformation and pH of the solution. Electrospray mass spectrometry can reveal the degree of protein folding from the distribution of charges imparted to the protein molecule. Additional information about protein-ligand affinity can be derived by fragmenting the complex using MS-MS. Another analytical tool not often combined with mass spectrometry but which can also illuminate information about protein structure and ligand binding is NMR. In the Special Feature the laboratories of Grandori at the University of Milano-Bicocca and Molinari at the University of Verona use these two analytical tools to study the binding of human liver fatty acid binding protein (hL-FABP) with two fatty acids, oleic acid or palmitic acid. The complementarity of the tools are shown. From ligand titrations ESI-MS shows that a maximum number of fatty acid molecules bind with hL-FABP with a peferential affinity for oleic acid over palmitic acid while titration studies with 13C NMR and 2D NMR reveal additional information suggesting polarity interactions drive the binding as well as solvent accessability to the binding sites within the folded protein.