Post-translational modification of betaH-crystallin of bovine lens with aging

This study investigates post-translational modification of proteins of bovine lens with aging (3 year old vs. 6 month old cows). After water-soluble proteins were submitted to gel and ion exchange chromatography, betaH-crystallin, a subunit of beta-crystallin, and modified materials were isolated. These materials were then submitted to two dimensional polyacrylamide gel electrophoresis (2D-SDS PAGE) to detect and isolate the new spots. Results for lens proteins from 3 year old animals were compared to those from 6 month old animals. All spots were digested in gel with trypsin and the molecular masses of tryptic digests were measured by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOFMS). Peptides peaks obtained from mass mapping were identified using the protein database of the MS-Fit program in the Protein prospector program of the University of California, San Francisco. We found that two post translational modifications of betaH-crystallin, acetylation and phosphorylation occurred with aging.