Intense chemiluminescence from the oxidation of luminol with m-chloroperoxybenzoic acid catalyzed by Mn(III)-microperoxidase Original Research Article

We have studied the chemiluminescence (CL) of luminol oxidation with m-chloroperoxybenzoic acid (mCPBA) or hydrogen peroxide (H2O2) catalyzed by Mn(III)-microperoxidase 8 (Mn(III)-MP8) using the stopped-flow technique. The CL involving Mn(III)-MP8 is two to three times as intense as that of the corresponding Fe(III)-MP8, while using mCPBA in place of H2O2 as the oxidant enhances the CL by 12–18-fold at the optimum pH (∼12). The rapid formation of the intermediate, OMn(IV)-MP8, upon addition of mCPBA to Mn(III)-MP8 will lead to a fast CL cycle. This in turn, will produce an intense CL of very short duration. The ratio of the peak CL intensity (mCPBA:H2O2) for the Mn(III)-MP8 system remains essentially constant (∼20) regardless of the pH and the concentrations of oxidant and luminol used, provided that the supply of the oxidant and luminol is sufficient. The novel use of Mn(III)-MP8/mCPBA for the CL of luminol oxidation will have a great analytical potential for very sensitive assays.