Scientists have learned that zinc plays an important role in the normal function of rhodopsin, a protein in the eye implicated in retinitis pigmentosa, a hereditary disease that often leads to blindness.

Without binding to zinc, “rhodopsin is very unstable, a feature that is typical of retinitis pigmentosa,” Dr. John Hwa from Dartmouth Medical School in Hanover, New Hampshire, told Reuters Health. “This has implications for therapy for retinitis pigmentosa where zinc concentration in the retina may be important.”

The researchers identified a zinc-binding site in rhodopsin, according to the report in the Journal of Biological Chemistry. Some cases of retinitis pigmentosa appear to occur because mutations near the site prevent zinc from binding properly.

According to Hwa, too little zinc in the body or a mutation in the binding site makes rhodopsin function abnormally, resulting in degeneration of the retina and eventually blindness.

He acknowledged that his team has yet to determine how much zinc is needed to prevent this problem.

SOURCE: Journal of Biological Chemistry, August 20, 2004.