Molecular Basis of the Structural Stability of Hemochromatosis Facto E: A Combined Molecular Dynamic Simulation and GdmCl-Induced Denaturation Study

Hemochromatosis factor E (HFE) is a member of class I MHC family and plays a significant role in the iron homeostasis. Denaturation of HFE induced by guanidinium chloride (GdmCl) was measured by monitoring changes in [theta](222) (mean residue ellipticity at 222 nm), intrinsic fluorescence emission intensity at 346 nm (F-346) and the difference absorption coefficient at 287 nm (Delta is an element of(287)) at pH 8.0 and 25 degrees C. Coincidence of denaturation curves of these optical properties suggests that GdmCl-induced denaturation (native (N) state <-> denatured (D) state) is a two-state process. The GdmCl-induced denaturation was found reversible in the entire concentration range of the denaturant. All denaturation curves were analyzed for Delta G(D)(0), Gibbs free energy change associated with the denaturation equilibrium (N state <-> D state) in the absence of GdmCl, which is a measure of HFE stability. We further performed molecular dynamics simulation for 40 ns to see the effect of GdmCl on the structural stability of HFE. A well defined correlation was established between in vitro and in silico studies. (C) 2015 Wiley Periodicals, Inc.