Fluorescent and compositional changes in crystallin supramolecular structures in pig lens during development

Water soluble proteins (WSPs) in Sus scrofa lenses from pigs in different developmental stages: (young (GI), young adult (GII), and middle-aged (GIII)) were separated using GF-HPLC, yielding fractions of different molecular weights. Non-tryptophan (345 / 420 nm) and tryptophan (280 / 345 nm) fluorescence was measured in these fractions. Relative non-tryptophan fluorescence increased with age at a rate directly correlated to the molecular weight of aggregates forming the different chromatographic fractions, while tryptophan fluorescence tended to decrease. The crystallins constituting each fraction were separated using 2D-electrophoresis and after development with Coomassie blue they were identified using MS-TOF. Also, the protein content of each spot was quantified by subsequent scanning and integration. The proportions of unchanged crystallins characteristically changed with age in chromatographic fractions of different molecular weights. Thus it was possible to relate these changes with those occurring in the fluorescent properties and molecular weight of supramolecular structures.