Rate constants for the reactions of OH radicals with the enzyme proteins as determined by the p-nitrosodimethylaniline method

Rate constants for the reactions of OH radicals with commonly occuring amino acids and several enzyme proteins were determined by the competition kinetics using p-nitrosodimethylaniline. From the assumption that the reaction of OH radicals with an amino acid residue is restricted to the surface region of enzyme molecule, an estimation of rate constant for the reaction of OH radicals with enzyme was attempted. The calculated values for cytochrome c and lysozyme were in good agreement with those obtained experimentally.