Thermal aggregation of ␤ L -crystallin was higher in the presence of peptide fragments generated from oxidized and trypsin-digested ␤ L -crystallin compared with thermal aggregation of the control proteins without oxidized ␤ L -crystallin fragments. Increased aggregation of ␤ L -crystallin was also observed despite the presence of ␣-crystallin (which has anti-aggregating properties) in the system. Self-aggregation of the oxidized ␤ L -crystallin fragments per se was not observed under the

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... mental conditions. Reverse-phase HPLC analysis of the precipitate obtained after heating a mixture of ␤ L -crystallin and oxidized ␤ L -crystallin fragments revealed that more than one peptide co-precipitates with ␤ L -crystallin. Electrospray mass spectrometry analysis of the peptides revealed that the molecular weight(s) of the peptides ranged from 1400 -1800. Tandem mass spectrometry and a data base search revealed that two of the peptides originated from ␤A4-crystallin (LTIFEQENFLGR, residues 121-132) and ␤B3-crystallin (AINGTWVGYEFPGYR, residues 153-167) respectively. Oxidized synthetic peptides representing the same sequence were also found to enhance the aggregation of ␤ L -crystallin in a manner similar to oxidized lens ␤ L -crystallin peptides. These data suggest that the polypeptides generated after oxidation and proteolysis of ␤ L -crystallins interact with denaturing proteins and facilitate their aggregation and light scattering, thus behaving like anti-chaperones. 1 The abbreviations used are: ADH, alcohol dehydrogenase; HPLC, high pressure liquid chromatography; ESIMS, electrospray ionization mass spectrometry; MS, mass spectrometry.