Non-tryptophan fluorescence of crystallins from normal and cataractous human lenses.

The soluble proteins of a newborn human lens exhibit almost no non-tryptophan fluorescence. On aging, an increase in the fluorescence of all native crystallins is found except for gamma 2-crystallin. With formation of nuclear cataract, a further increase is seen for gamma 1-crystallin. The fluorophore, excitation 355 nm/emission 420 nm, is mainly associated with one species of the gamma 1-crystallin population. It is also present as such in the soluble fraction and increases significantly with nuclear cataract formation. At least one of the gamma 1-crystallins seems to play an important role in the cataractogenic process.