The Reaction of Chymotrypsin with 2,3-Butanedione Trimer

Abstract

A method for the preparation of the trimer of 2,3-butanedione has been developed. The reaction of this trimer with chymotrypsin Aα was examined in the presence or absence of light. Under conditions of exclusion of light, modification of one to two arginine residues and of a similar number of lysine residues could be achieved without any loss of enzymatic activity. The trimer facilitated a rapid photoinactivation of the enzyme with little or no modification of the above amino acid residues. Such photoinactivation was not promoted by the monomer 2,3-butanedione. Enzyme irradiated in the presence of the trimer was found to react with proflavine and diisopropylfluorophosphate to an extent greater than that expected on the basis of residual activity present. Proflavine protected the enzyme from the trimer promoted photoinactivation.