ABSTRACT
This chapter considers the reaction of arginyl residues in proteins with three different reagents; phenylglyoxal, 2, 3-butanedione, and 1, 2-cyclohexanedione since the vast majority of reports during used these reagents. It is noted that several other reagents have been used for the modification of arginine. The fluorescence properties of the reaction product between ninhydrin and guanidino compounds such as arginine have provided the basis for the use of ninhydrin for the detection of guanidine compounds in biological fluids following separation by high performance liquid chromatography. The high pKa of the guanidine functional group necessitated fairly drastic reaction conditions to generate an effective nucleophile. Most proteins are not stable to extreme alkaline pH. The modification of arginyl residues was however possible and the early efforts in this area have been reviewed. 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.
