Intermolecular disulfide bonding of lens membrane proteins during human cataractogenesis

Two-dimensional diagonal electrophoresis has been used to characterize intermolecular disulfide bonding of membrane proteins from lenses of cataractous and normal patients. A component of approximately 18,000 daltons, linked via intermolecular disulfide bonding, was found in membrane preparations from 10 of 17 cataracts studied. In comparison, membrane from only 1 of 12 normal lenses of approximately the same age range was found to contain intermolecular disulfide bonding of a component of similar molecular weight. Treatment of normal lens with the oxidizing agents cupric sulfate and 1,10-phenanthroline resulted in intermolecular disulfide bonding of the 18K component in a manner similar to that found in cataractous lenses. Together these results demonstrate that human cataractogenesis is many times accompanied by intermolecular disulfide bonding of a membrane component of 18K and suggest that this intermolecular bonding may be the result of the previously reported oxidative insult of the lens during human cataract formation.