Although proteins are generally composed of L-alpha-amino acids, D-beta-aspartic acid (Asp)-containing proteins have been reported in various elderly tissues. Our previous study detected several D-beta-Asp-containing proteins in a rabbit lens derived front epithelial cell line by Western blot analysis of a 2D-gel using a polyclonal antibody that is highly specific for D-P-Asp-containing proteins. The identity of each spot was subsequently determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and the Ms-Fit online database searching algorithm. In this Study, we discovered novel D-beta-Asp-containing proteins from rabbit lens. The results indicate that beta-crystallin A3, beta-crystallin A4, beta-crystallin B1, beta-crystallin B2, beta-crystallin B3, gamma-crystallin C, gamma-crystallin D, and lambda-crystallin in rabbit lens contain D-beta-Asp residues. Furthermore, the occurrence of D-beta-Asp residues increases with infrared ray (IR) irradiation. Additionally, some D-beta-Asp-containing proteins only appear after IR irradiation. One such protein is the cc-enolase, which shows homology to tau-crystallin. (c) 2006 Elsevier Inc. All rights reserved.