eye-lens protein y-crystallin

Although ubiquitous, no universal function can be confidently ascribed to glutathione. The eye lens maintains higher concentrations of reduced glutathione within its cells than do other tissues (Waley, 1969). The ratio of protein thiol to reduced glutathione in most species of lens is about 5:1 (Kuck et al., 1982). The requirement for glutathione in maintaining a transparent lens is indicated by the observation that concentrations decline in nearly all forms of cataract (Kinoshita, 1964), with the possibility of some glutathione becoming protein-bound (Harding, 1970; Anderson & Spector, 1978). Furthermore, human cataract formation is often associated with oxidation of lens proteins (Augusteyn, 1981; Harding, 1981; Spector, 1984). Kinoshita (1964) has suggested that the high concentration of glutathione in lenses may serve to protect thiol groups from oxidation to disulphides, even though, as he points out, glutathione was found to be more readily oxidized than bovine lens proteins (Kinoshita & Merola, 1959). The rate of synthesis of glutathione is high in