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 72-crystallin. With formation of nuclear cataract, a further increase is seen for 7,-crystallin. The fluorophore, excitation 355 nm/emission 420 nm, is mainly associated with one species of the Yi-crystallin populatio...