Specific labeling of lens aldehyde dehydrogenase class 1 from (3)H-cholesterol or its derivatives.
We investigated the possibility that sterols could covalently modify ocular lens cell proteins. Incubation of cultured bovine lens epithelial cells (BLEC) with (3)H-cholesterol led to the labeling of a cytosolic protein of about 52 kD. Two-dimensional electrophoresis of the BLEC soluble proteins and fluorography revealed one labeled protein of 52 kD, pI = 6.6, plus a weakly labeled, slightly more acidic protein of the same size. MALDI-MS analysis of both proteins recovered from duplicate gels indicated both to be aldehyde dehydrogenase class 1 (ALDH-1). The identity was confirmed by immunoprecipitation with antiserum to ALDH-1. Alkaline hydrolysis of (3)H-labeled ALDH-1 released most of the radiolabel as compounds much more polar than cholesterol. We speculate that lens ALDH-1 can participate in the oxidation of cholesterol or its derivatives to unidentified sterol carboxylic acids and that the labeled protein reflects capture of ALDH-1 with sterol intermediates covalently bound to the enzyme in ester linkage. Lens ALDH-1 might, therefore, participate in the detoxication of polar sterols.
Cenedella
R J
RJ
Department of Biochemistry, Kirksville College of Osteopathic Medicine, 800 West Jefferson, Kirksville, MO 63501, USA. rcenedella@kcom.edu
D000444:Aldehyde Dehydrogenase / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology*; D003459:Crystallins / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology; D007908:Lens, Crystalline / Q000187:drug effects* / Q000201:enzymology; D008970:Molecular Weight; D010084:Oxidation-Reduction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013194:Staining and Labeling
D003459:Crystallins; D002784:Cholesterol; D000444:Aldehyde Dehydrogenase