Detection of glycated polypeptides in human aqueous humor by lectin-binding analysis

The proteins from 30 samples of normal human aqueous humor were separated into major fractions by sodium dodecyl-sulfate polyacrylamide gel electrophoresis, transferred to nitrocellulose, and probed with lectins to characterize the glycated polypeptides. The lectins used were derived from Canavalia ensiformis (concanavalin-A), Phaseolus vulgaris (erythroagglutinin), Arachis hypogaea (peanut agglutinin), and Ulex europaeus agglutinin-I. Using this microanalytical technique, the glycated polypeptides in the aqueous humor were separated into nine major fractions with apparent molecular weights of 17, 41, 50, 55, 61, 77, 80, 120 and 151 kDa. The predominant oligosaccharides detected on these fractions were complex chains usually with sialic acid residues. The possible roles of the glycated polypeptides in the aqueous humor in health and disease are discussed. Our investigation of these molecules in human aqueous humor provides baseline data for a rapid diagnostic analysis of microsamples of this fluid obtained from diseased eyes.