Fluorescent probe development for specific determination of halogenating activity of enzymes myeloperoxidase and eosinophil peroxidase

Abstract

Peroxidases are enzymes which catalyze the oxidation of different substrates from the reduction of hydrogen peroxide. The peroxidases present in leukocytes, myeloperoxidase (MPO) and eosinophil peroxidase (EPO), are characterized by their exclusive catalytic capacity in the oxidation of chloride and bromide to hypochlorous acid (HOCl) and hypobromous (HOBr), respectively. These oxidants are characterized by their intense reactivity and implications in several deleterious processes, which are well established and accepted by the scientific community. The determination of the enzymatic activity of these enzymes is not so trivial, because in addition to acting through its halogenating cycle (production HOCl and HOBr), these enzymes also act on various substrates through its peroxidase cycle. Thus, the available methods for the determination the halogenating activity are often indirect and/or of low selective. Here, based on a recent discovery of our research group, we intend to develop a direct and selective method for the determination of halogenating activity of these enzymes. Our proposal is the application of a fluorescent probe (dansylglycine), which reacts readily with HOBr, due to its electrophilic character, but is not reactive with others oxidants. Thus, our hypothesis is that we could correlate the halogenating activity of these enzymes with the change in fluorescence of this probe and, consequently, to propose a new analytical technique for those who need to study processes in which these enzymes are involved. (AU)