Article ID Journal Published Year Pages File Type
2089061 Journal of Immunological Methods 2007 11 Pages PDF
Abstract

N-formylkynurenine and kynurenine are oxidation products of tryptophan formed from the reaction catalyzed by indoleamine 2,3-dioxygenase. These kynurenines react with proteins to produce chemical modifications in the lens. We developed a novel monoclonal antibody that detects a kynurenine modification in proteins. The antibody recognized proteins (human lens proteins, RNase A and BSA) that were modified by either kynurenine or N-formylkynurenine. The antibody also reacted strongly with N-formylkynurenine-modified Nα-acetyl histidine and weakly with N-formylkynurenine-modified Nα-acetyl lysine, Nα-acetyl cysteine and Nα-acetyl arginine. The antibody recognized kynurenine and N-formylkynurenine but not other tryptophan oxidation products. We isolated and purified a major antigen from the reaction mixture of Nα-acetyl histidine and N-formylkynurenine and identified the product as N-acetyl-1-[3-(2-aminophenyl)-1-carboxy-3-oxopropyl]-histidine. We then used our purified antibody to detect kynurenine modifications in kynurenine-treated human lens epithelial cells and human lens. We found epithelial immunoreactivity in a lens from an aged donor but not in one from a very young donor. This would suggest that the antibody detects age-related changes in lens proteins altered by kynurenines. We believe that our antibody could be used to establish the importance of kynurenine modifications in diseases where tryptophan oxidation is enhanced.

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