Preferential interaction among lens proteins as evidenced from accessibility of crystallins to ammonia gas

Different crystallins (α, β_H, β_L and low molecular weight-LMW) were isolated from bovine lenses. The study of accessibility of the lyophilized solid proteins to ammonia gas was conducted in a high-vacuum vapor sorption apparatus. The sorption and desorption isotherms obtained were used to calculate the sorptive capacity and retentive capacity (hysteresis and irreversibly sorbed ammonia gas) of the different proteins. Individual crystallins were used to study the accessibility of the self-aggregates. Protein mixtures (β_H + β_H; α + LMW, etc.) were employed to study the accessibility of binary, tertiary and finally quaternary systems to ammonia vapor. Finally lyophilized thin sections of the bovine lenses were exposed to ammonia vapor. Comparing the sorptive and retentive capacities of self- and hetero-aggregates gave an indication of the preferred interactions among lens proteins in free solution, and by inference in situ, in the lens fibers.