Crystallins, the major proteins of the lens, undergo rapid partial cleavage during lens maturation and aging. Cleavage of crystallins takes place in both animal an human lenses. Since cataracts in animals have been associated with an acceleration of this process, the principal investigator hypothesizes that human cataracts may also result from the inappropriate cleavage of crystallins. To test this hypothesis the PI proposes: 1) Isolating and characterizing the unidentified proteolytic enzyme responsible for the majority of protein fragmentation in human lens. 2) Producing detailed maps on two-dimensional electrophoresis gels of the identities of both intact and modified lens proteins found in animal and human lenses. 3) Creating a standardized two-dimensional electrophoresis database for lens proteins for access on the World Wide Web. This work will be performed using matrix assisted laser desorption mass spectrometric analysis of protease substrates and two-dimensional electrophoretically separated lens proteins. These studies are important because 1) the enzyme causing the fragmentation of human lens crystallins is unknown; 2) little information comparing the identities and modifications of proteins in animal and human lenses now exists; and 3) no mechanism for easily sharing lens protein data between researchers is available. The long term goals of this project are to: improve methods used to study protein modifications in the lens, develop appropriate animal models to study human cataract, test if protein fragmentation may be a cause of human cataract, and develop protease inhibitors as possible anticataract drugs.
