title: Extraction of the functional manganese and calcium from photosystem II.
abstract: Manganese (Mn) and calcium (Ca) are both metal cofactors required for photosynthetic oxygen evolution. The functional roles for these ions in the O2-evolving reactions are not completely known. They are studied by comparative spectroscopic measurements between intact and metal-depleted samples. In this chapter, we outline three experimental procedures used for the various removal of Mn and Ca from photosystem (PS) II-containing (i.e,. O2-evolving) preparations: the complete Mn extraction using a strong alkaline Ches buffer (pH 9.4)/MgCl2 wash, partial Mn extraction using a mild hydroxylamine (pH 6.8) wash, and specific Ca extraction through a low pH/citrate (pH 3) wash. The O2 evolution activities (measured by a Clarke-type oxygen electrode), protein composition (determined by sodium dodecyl sulfate- polyacrylamide gel electrophoresis), and the relative Mn and Ca content (measured by atomic absorption spectroscopy) are reported for each extraction procedure.
authors.affiliation: Photobioenergetics, Research School of Biological Sciences, The Australian National University, Canberra, Australia.
authors.forename: Joel
authors.initials: J
authors.lastname: Freeman
authors.forename: Garth
authors.initials: G
authors.lastname: Hendry
authors.forename: Tom
authors.initials: T
authors.lastname: Wydrzynski
mesh_terms: D002118:Calcium / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D018724:Spinacia oleracea / Q000737:chemistry / Q000166:cytology; D020524:Thylakoids / Q000737:chemistry
chemical_list: D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D008345:Manganese; D010100:Oxygen; D002118:Calcium