Glutathione and its function in the lens--an overview.

This paper presents an overview of the current state of our knowledge concerning the metabolism and function of glutathione (GSH) in the lens, with particular reference to the contributions of Dr Jin H. Kinoshita to this field. Glutathione in the lens is synthesized from its constituent amino acids and degraded by mechanisms involving transpeptidation and hydrolysis. The turnover of GSH in the lens is due to its catabolism rather than transport of GSSG as is the case in red blood cells and some other tissues. Three aspects of the functional role of GSH in cataract formation are considered. First, GSH may be important in maintaining protein thiols in the reduced state, thus preventing the formation of high molecular weight protein aggregates which are the basis for light scattering and lens opacification. A second function may be to protect membrane -SH groups that are important in cation transport and permeability. A third functional role is to detoxify hydrogen peroxide and other organoperoxides. The glutathione redox cycle is intimately involved in the detoxification of H2O2 which is normally present in the aqueous humor.