Butanedione reaction with arginine

Yankeelov et al. (1968) have reported that the trimer of 2,3-butanedione (I) as well as the dimer (II) are the reactive forms of this reagent. Reaction conditions for the exhaustive modification 

Since the reagent readily reacts with amino groups at the relatively high concentrations required for complete derivatization of the protein, protection of the -amino group is essential if specific cleavage by trypsin at lysine residues is desired. A possible method of protection prior to derivatization with compound I would involve citraconylation of the lysine residues prior to reaction. 

Riordan (1973) has reported that the monomer of 2,3-butanedione inactivates carboxypeptidase as effectively as the trimer. One interesting feature of his study is that a 0.05 M borate buffer enhances the rate and possibly affects the distribution of products formed from both monomeric and trimeric butanedione when compared with a 0.05 M veronal buffer at the sample pH. He has attributed this specific buffer effect to the formation of a cyclic borate ester following the initial condensation of the guanidinium group with 2,3-butanedione as indicated in eq. (3.1). The conditions of modification with butanedione used by Riordan (1973) involved incubation of the protein at pH 7.5 at 20°C for 15-60 min at concentrations of butanedione ranging from 2.2 x 10 M to 7.5 X 10-2 

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Arginine Phenylglyoxal Butanedione Phenylglyoxal can react with lysine Butanedione should be used in the dark to prevent reaction with tryptophans, histidines, and tyrosines... 

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