Accessibility of low-molecular-weight crystallins to ammonia and hydrogen chloride gases

Low-molecular-weight crystallin was isolated from bovine lenses. Its purity was established by high-pressure liquid chromatography (HPLC) and sodium dodecyl sulfate (SDS)-gel electrophoresis. The amino-acid composition, in general, and the total available acidic and basic sites, in particular, were obtained by amino-acid analysis. The accessibility of low-molecular-weight crystallins to ammonia and hydrogen chloride vapor was obtained by high vacuum vapor sorption. The sorption and desorption isotherms were analysed regarding the gas uptake at different vapor pressures. The amount of ammonia and hydrogen chloride irreversibly sorbed and retained as well as the hysteresis imply high accessibility of crystallins to the polar gases. The results indicate that molecular self aggregation of low-molecular-weight crystallins in solid state occurs mostly through hydrophobic domains.