Accessibility of crystallins to HCI gas

Different crystallins (alpha, beta H, beta L and LMW) were isolated from bovine lenses. Lyophilized samples of single components (homoaggregates) and those of mixtures (heteroaggregates) were exposed to HCI vapor in a high vacuum vapor sorption apparatus. Lyophilized 5-microns sections of bovine lens were similarly exposed to HCI vapors. Sorption and desorption isotherms were obtained at two temperatures on all samples. Fourier transform infrared (FT IR) spectroscopy was conducted on solid samples of crystallin with and without irreversibly sorbed HCI gas. From the IR spectra the nature of interaction between HCI and protein were ascertained. From the sorption parameters, mainly from the irreversibly sorbed HCI, the accessibilities of homo and hetero aggregates were calculated. The accessibilities provided information on the preferential interactions among crystallins. One of the main conclusions derived from this and also from previous ammonia sorption studies is that the supramolecular organization in the lens fibers is not governed solely by the thermodynamically preferential interactions of crystallins, but also by other possibly cytoskeletal organizations of crystallins.