Protein content in aqueous humor from patients with pseudoexfoliation (PEX) investigated by capillary LC...

Analysis of proteins in human body fluids is challenging since the composition of the sample often is rather complex. Here we present a method for analysis of proteins in aqueous humor from two groups of cataract patients, with and without pseudoexfoliation (PEX). Aqueous humor is an extracellular fluid contained in the anterior chamber of the eye between the cornea and iris. The limited volume of sample requires sophisticated analysis techniques. Our method is based on a total tryptic digestion of the sample followed by capillary LC-MALDI MS and MS/MS analysis of the peptides. The method is rapid, efficient and suitable as a complement or alternative to more commonly used methods based on gel electrophoretic experiments. With this method we found and unambiguously identified 30 nonredundant proteins. Proteins found include general transport proteins such as albumin and apolipoprotein A1 but also specific proteins involved in immune response, such as complement factors. Cystatin C, clusterin, and crystallins were also found. Although the number of proteins was roughly the same in both groups there was a significant difference in their identities. These findings may give some new insights into the pathophysiology of the PEX syndrome.