DYNAMICS OF HUMAN INTENSTINAL FATTY ACID BINDING PROTEIN

Abstract

Biological macromolecules such as proteins exist in dynamic equilibrium in which a lower energy ground state interconverts with one or more ?exited states?. Currently, studies on the multistate systems are often limited to three-state exchange models at most due to the high level of complexity increased with the number of the exchanging states. Here we present a millisecond timescale dynamics study of apo-form human intestinal fatty acid binding protein (hIFABP) using 15N NMR CPMG and CEST experiments. Based on our observations, we propose that the excited states in equilibrium are irrelevant to the ligand binding process. The FABP-ligand binding should be via a ligand-induced binding mechanism in which the ligand interacts with the native state directly. In the absence of any unfolded states, the three intermediates should represent conformations in the last step of the independent multitrack protein folding pathway.