Defining the involvement of HOCl or Cl2 as enzyme-generated intermediates in chloroperoxidase-catalyzed reactions.

摘要: Peroxidatic substrates, catechol (CAT) and 2,4,6-trimethylphenol (TMP) were used as probes of thechloride dependent reactions catalyzed by chloroperoxidase (CPO). TMP is consumed only in the presence chloride. a competitive inhibitor versus CAT, but CAT noncompetitive chloride-dependent CPO-catalyzed peroxidation reactions. The ratio CPO reaction direct competition studies increases chloride concentration increased from 1.0 to 400 mM. Ratios non-enzymatic HOCl under conditions otherwise similar those are relatively insensitive changes experimentally indistinguishable values attained enzyme system at high concentrations. Comparison enzymatic ratios with indicate that proportion involving freely dissociable, enzyme-generated, oxidized halogen species varies 10% low concentrations essentially 100% All data consistent mechanism which competes for binding both compound I chlorinating intermediate (EOCl). Chloride leads formation EOCl initiates pathway. When binds either or EOCl, it directly product. induces release reacts produce Cl2, released enzyme. compete free species. This first evidence kinetically significant involvement an any reaction.