title: Manganese binding to the 23 kDa extrinsic protein of Photosystem II.
abstract: The recombinant form of the extrinsic 23 kDa protein (psbP) of Photosystem II (PSII) was studied with respect to its capability to bind Mn. The stoichiometry was determined to be one manganese bound per protein. A very high binding constant, K(A)=10(-17) M(-1), was determined by dialysis of the Mn containing protein against increasing EDTA concentration. High Field EPR spectroscopy was used to distinguish between specific symmetrically ligated Mn(II) from those non-specifically Mn(II) attached to the protein surface. Upon Mn binding PsbP exhibited fluorescence emission with maxima at 415 and 435 nm when tryptophan residues were excited. The yield of this blue fluorescence was variable from sample to sample. It was likely that different conformational states of the protein were responsible for this variability. The importance of Mn binding to PsbP in the context of photoactivation of PSII is discussed.
authors.affiliation: Institut für Biologie II, Biochemie der Pflanzen, Universität Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
authors.forename: Natallia
authors.initials: N
authors.lastname: Bondarava
authors.forename: Sun
authors.initials: S
authors.lastname: Un
authors.forename: Anja
authors.initials: A
authors.lastname: Krieger-Liszkay
mesh_terms: D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology; D007700:Kinetics; D008345:Manganese / Q000378:metabolism*; D008970:Molecular Weight; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D002614:Chelating Agents; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D011994:Recombinant Proteins; D008345:Manganese; D004492:Edetic Acid