Stability of normal and aging lens gamma crystallins

Fluorescence polarization and near UV circular dichroism (CD) studies were performed on four purified human gamma crystallin fractions derived from normal (eye bank lenses) ranging in age from the first decade through the seventh decade. All the four young (first decade) gamma crystallins had higher polarization values compared with the old (sixth and seventh decade) fractions: in addition, the CD spectra of the gamma I and II crystallins show substantial aging differences; marked decrease in intensity of the negative tryptophan band near 290 nm. While this effect is much less pronounced in the gamma III and IV fractions, aging changes in other areas of some of these fractions also occur. These data demonstrate significant alterations occurring in the human gamma crystallins associated with the normal aging process. Specific conformational alterations are proposed to account for these changes.