Inhibition of E. coli L-Asparaginase by reaction with 2,3-butanedione. Chemical modification of arginine and histidine residues.

The inactivation of E. coli asparaginase by 2,3-butanedione studied with L-asparagine and diazooxonorvaline as substrates obeys pseudo first order kinetics. Activity losses are linear with respect to arginine and histidine modification, with complete inactivation being correlated with alteration of one arginine and one histidine per subunit. The rate of inactivation of the enzyme was reduced in the presence of competitive inhibitors like L-2-amino-2-carboxyethane-sulfonamide. Under comparable conditions 1,2-cyclo hexanedione does not affect the activity of L-asparaginase.