Kinetic method for assaying the halogenating activity of myeloperoxidase based on reaction of celestine blue B with taurine halogenamines.
Myeloperoxidase (MPO) is a challenging molecular target which, if put under control, may allow regulating the development of inflammatory reactions associated with oxidative/halogenative stress. In this paper, a new kinetic method for assaying the halogenating activity of MPO is described. The method is based on measuring the rate of iodide-catalyzed oxidation of celestine blue B (CB) by oxygen and taurine N-chloramine (bromamine). The latter is produced in a reaction of taurine with HOCl (HOBr). CB is not a substrate for the peroxidase activity of MPO and does not react with hydrogen peroxide and superoxide anion radical. Taurine N-chloramine (bromamine) reacts with CB in molar ratio of 1:2. Using the new method, we studied the dependence of MPO activity on concentration of substrates and inhibitors. The specificity of MPO inhibition by non-proteolyzed ceruloplasmin is characterized. The inhibition of taurine N-chloramine production by neutrophils and HL-60 cells in the presence of MPO-affecting substances is demonstrated. The new method allows determining the kinetic parameters of MPO halogenating activity and studying its inhibition by various substances, as well as screening for potential inhibitors of the enzyme.
['Sokolov|A V|AV|', 'Kostevich|V A|VA|', 'Kozlov|S O|SO|', 'Donskyi|I S|IS|', 'Vlasova|I I|II|', 'Rudenko|A O|AO|', 'Zakharova|E T|ET|', 'Vasilyev|V B|VB|', 'Panasenko|O M|OM|']
D001965:Bromides D002570:Ceruloplasmin D004396:Coloring Agents D057075:Enzyme Assays D004791:Enzyme Inhibitors D018922:HL-60 Cells D054879:Halogenation D006801:Humans D007700:Kinetics D009504:Neutrophils D010078:Oxazines D009195:Peroxidase D013654:Taurine
halogenating activity myeloperoxidase celestine blue B taurine HOCl ceruloplasmin