Chemical modification of the arginines in transferrins.

Abstract

Phenylglyoxal, 2,3-butanedione, and 1,2-cyclo- hexanedione were used to modify the arginines in ovotrans- ferrin and human serum transferrin. As much as 88% of the arginines of iron-free ovotransferrin was modified with a 7.5-fold excess of 2,3-butanedione in 200 mM borate. The iron-binding activity decreased to 50% in this reaction. The rate and extent of arginine modification and inactivation of the protein were directly related to the concentration of borate in solution. When borate was removed from the modified protein solution, the iron-binding activity increased from 50 to 80% and some of the arginine was regenerated. Cyclohexanedione also inactivated the protein in borate buffer but was not used T 1, he transferrins are a group of metal-binding proteins found