Revised Manuscript Received June 22, 1995® abstract: Advanced glycation end products (AGEs) and glycoxidation products are formed during Maillard or browning reactions between sugars andproteins and are implicated in the pathophysiology of aging and the complications of diabetes. To determine the structure of AGEs, antibodies were prepared to protein browned by incubation with glucoseand used in ELISA assays to measure AGEs formed in model reactions between bovine serum albumin (BSA) or/Va-acetyllysine and glucose, fructose, or glyoxal. AGEs were formed from glucoseand fructose only under oxidative conditions, but from glyoxal under both oxidative and antioxidative conditions. Gel permeation chromatographic analysis indicated that a similar AGE was formed in reactions of/W-acetyllysine with glucose, fructose, and glyoxal and that this AGE co-eluted with authentic/Va-acetyl-/Ve-(carboxymethyl) lysine. Amino acid analysis of AGE proteins revealed a significant content of (Ve-(carboxymethyl) lysine (CML). In ELISA assays using polyclonal antibodies against AGE proteins, CML—BSA (~ 25 mol of CML/mol of BSA), prepared by chemical modification of BSA, was a potent inhibitor of the recognition of AGE proteins and of AGEs in human lens proteins. We conclude that AGEs are largely glycoxidation productsand that CML is a major AGE recognized in tissue proteins by polyclonal antibodies to AGE proteins.

The term advanced glycosylation (glycation) end product (AGE) 1 was introduced by Vlassara et al.(1984) to describe the brown, fluorescent, and cross-linked structures formed during late stages of the Maillard reaction betweensugars and proteins in vivo. Age-dependent structuraland functional alterations in proteins resulting from accumulation of AGEs are now implicated in the development of pathophysiology of normal aging and in the pathogenesis of long-term