Spectroscopic, ligand binding, and enzymatic properties of the spleen green hemeprotein. A comparison with myeloperoxidase.

摘要: The bovine spleen green hemeprotein, a peroxidase which exhibits spectrophotometric properties similar to those of granulocyte myeloperoxidase, was purified using an improved method. ligand affinity the ferric enzyme spectroscopically determined chloride and cyanide as exogenous ligands. pH dependence apparent dissociation constant enzyme-chloride complex showed presence proton dissociable group with pKa value 4 on enzyme; binds when this is protonated 60 microM. also regulated by 4, but in case unprotonated 0.6 microM; only protonated, uncharged form reacts enzyme. Cyanide binding competitively inhibited chloride, cyanide. EPR spectrum resting exhibited rhombic high spin signal at g = 6.65, 5.28, 1.97 low 2.55, 2.32, 1.82. Upon formation complex, replaced new g-values 6.81, 5.04, 1.95. 2.83, 2.25, 1.66. Examination enzymatic activity hemeprotein following chlorination monochlorodimedon has indicated that same chlorinating myeloperoxidase; can catalyze hypochlorous acid from hydrogen peroxide ion. Comparison present data myeloperoxidase led conclusion structure iron center its vicinity very similar, if not identical, myeloperoxidase. thus be used model study active center, environment,