Identification of the major components of the high molecular weight crystallins from old human lenses.

High molecular weight aggregates from the water soluble portion of four lenses from older donors were examined by mass spectrometric techniques that permitted unambiguous identification of the principal components as alpha A-, alpha B- and gamma s-crystallins. Post-translational modifications that were located and identified included deamidations in alpha A and gamma s and an intramolecular disulfide bond in alpha A-crystallin. The C-terminus of alpha A was not found, supporting previous suggestions that this portion of the protein may be important in preventing aggregation.