COOXIDATION OF PHENOL AND 4-AMINOANTIPYRINE CATALYZED BY MICROPEROXIDASES AND MICROPEROXIDASE-PROTEIN COMPLEXES

The kinetic characteristics of co-oxidation of 4-aminoantipyrine (AAP) and phenol or p-iodophenol at different hydrogen peroxide concentrati ons were compared with microperoxidases MP-8, MP-9, MP-11, horseradish peroxidase (HRP), and peroxidase of Arthromyces ramosus (ARP). Peroxi dase activity increases in the sequence HRP > ARP > MP-9 > MP-8 > MP-1 1. Complexing the microperoxidases with human serum albumin (HSA) at 1 :1 ratio helps retain the peroxidase activity at a constant level at h igh H2O2 concentrations. The heme is protected against destruction by active radicals. Monoclonal antibodies (AB) against porphyrin decrease the peroxidase activity of three microperoxidases with respect to AP and phenol co-oxidation and protect the heme. Inert proteins (HSA, ova lbumin) are practically without effect on HRP activity, whereas specif ic antibodies against the enzyme drastically activate HRP at high hydr ogen peroxide concentrations by forming an immune complex precluding t he dissociation of HRP into heme and the apoenzyme.