Natural ligand binding and transfer from liver fatty acid binding protein (LFABP) to membranes

Abstract

Liver fatty acid-binding protein (LFABP) is distinctive among fatty acid-binding proteins because it bindsmore than one molecule of long-chain fatty acid and a variety of diverse ligands. Also, the transfer offluorescent fatty acid analogues to model membranes under physiological ionic strength follows a differentmechanism compared to most of the members of this family of intracellular lipid binding proteins.Tryptophan insertion mutants sensitive to ligand binding have allowed us to directly measure the bindingaffinity, ligand partitioning and transfer to model membranes of natural ligands. Binding of fatty acids showsa cooperative mechanism, while acyl-CoAs binding presents a hyperbolic behavior. Saturated fatty acidsseem to have a stronger partition to protein vs. membranes, compared to unsaturated fatty acids. Naturalligand transfer rates are more than 200-fold higher compared to fluorescently-labeled analogues.Interestingly, oleoyl-CoA presents a markedly different transfer behavior compared to the rest of theligands tested, probably indicating the possibility of specific targeting of ligands to different metabolic fates.