Alpha-A crystallin: quantitation of C-terminal modification during lens aging.
Previous studies have demonstrated that the C-terminal region of alpha-A crystallin is susceptible to age-dependent, posttranslational modification. To quantitate the amount of modification, alpha-A crystallin was purified from total proteins of the aging bovine lens, then digested with lys-C endoproteinase. Reverse phase, high pressure liquid chromatography was used to resolve and quantitate the resulting peptides, to determine the amount of C-terminal peptide relative to peptides from other regions of the protein that have not been reported to undergo modification. The results indicate that relative to alpha-A crystallin from newborn lens, posttranslational modification has occurred in approximately 45-55% of the C-terminal region from mature lens. These results demonstrate extensive modification of the C-terminal region of alpha-A crystallin from the mature lens, indicating that during the aging process, posttranslational modifications in this region may make significant contributions to the aggregated state and/or molecular chaperone properties of the molecule.
Takemoto
L
L
Division of Biology, Kansas State University, Manhattan 66506.
Gopalakrishnan
S
S
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003459:Crystallins / Q000302:isolation & purification / Q000378:metabolism*; D007908:Lens, Crystalline / Q000737:chemistry / Q000502:physiology*; D010446:Peptide Fragments / Q000032:analysis*; D010449:Peptide Mapping; D011499:Protein Processing, Post-Translational
D003459:Crystallins; D010446:Peptide Fragments