title: pH-linked binding of Mn(II) to manganese peroxidase.
abstract: The stability of Mn(II) binding to manganese peroxidase (MnP) has been studied as a function of pH by spectrophotometric and potentiometric titrations. The sensitivity of the potentiometric titrations allows collection of data that are consistent with a high-affinity and a low-affinity Mn(II) binding site on the peroxidase. The two sites differ in affinity by 4 to 900-fold between pH 4 and 6.5. The stability of Mn(II) binding to the high-affinity site increases with increasing pH, while the stability of Mn(II) binding to the low-affinity site decreases with increasing pH. Interestingly, at pH values above 5.0, the high-affinity site appears to be partially unavailable for binding Mn(II). A pH-dependent structural change in the Mn(II) binding site is proposed to account for this partial inactivation at elevated pH.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.
authors.forename: M R
authors.initials: MR
authors.lastname: Mauk
authors.forename: K
authors.initials: K
authors.lastname: Kishi
authors.forename: M H
authors.initials: MH
authors.lastname: Gold
authors.forename: A G
authors.initials: AG
authors.lastname: Mauk
mesh_terms: D001487:Basidiomycota / Q000201:enzymology; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism*; D011199:Potentiometry; D011485:Protein Binding; D013053:Spectrophotometry; D055672:Static Electricity
chemical_list: D008345:Manganese; D010544:Peroxidases; C051129:manganese peroxidase