ABSTRACT

Until approximately 10 years ago the specific chemical modification of arginine was relatively difficult to achieve. The high pKa of the guanidine functional group necessitated fairly drastic reaction conditions to generate an effective nucleophile. The modification of arginyl residues with glyoxal has also been proposed. Specificity of reaction is a problem with reaction also at primary amine groups and sulfhydryl groups. The determination of the extent of arginine modification is generally determined by amino acid analysis after acid hydrolysis but conditions generally need to be modified to prevent loss of the arginine derivative. Of particular interest has been the observations of Fonda and Cheung that the reaction of arginine with phenylglyoxal is greatly accelerated in bicarbonate-carbonate buffer systems. The ability of 2,3-butanedione to act as a photosensitizing agent for the destruction of amino acids and proteins in the presence of oxygen was emphasized in work by Fliss and Viswanatha.