Spectroscopic studies of the protein-methylglyoxal adduct.

Abstract
Spectroscopic measurements are reported for the effects of pH, time, solvent and chemical modification of arginine and lysine side chains on the reaction of proteins with methylglyoxal. The reaction responsible for the appearance of a brown coloration and increased submolecular electronic activity in the proteins involves the .epsilon.-amino groups of the lysine residues. The primary step in the reaction evidently involves the formation of a Schiff base linkage between the lysine side chain and methylglyoxal. By the formation of Schiff bases, aldehydes can act as electron acceptors in charge transfer interactions with proteins.