title: The EXAFS study on the local structure of lanthanum in spinach PSII.
abstract: The complex of photosystem II (PSII) had been prepared from spinach by treatment with Triton X-100. The PSII, which had been depleted of the extrinsic 17- and 23-kDa polypeptides, was obtained by exposing the solution to a high concentration of NaCl, and the complex of PSII-La3+ was prepared by treatment with LaCl3. The result indicated that La3+ could inhibit the oxygen-evolution activity of PSII by replacing the Ca2+. The local structural environment of La in PSII has been also studied by using extended X-ray absorption fine structure (EXAFS). The primary result of EXAFS indicated that La coordinated with eight oxygen and/or nitrogen atoms, with the distance of the La-O/N bond being 2.5 A. In addition, La coordinated with four carbon atoms, with a distance of 3.5 A in the second shell. In the third shell, La coordinated with two manganese atoms, with the distance of La-Mn bond being 4.49 A, and it was also found that the La-Mn distance (4.49 A) was longer than that of Ca-Mn (3.3 A) (1) in PSII.
authors.affiliation: Department of Farmland Utilization, National Agriculture Research Center, Tsukuba City, Ibaraki Prefecture, Japan.
authors.forename: W J
authors.initials: WJ
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Tao
mesh_terms: D002118:Calcium / Q000737:chemistry; D007811:Lanthanum / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry; D015394:Molecular Structure; D010100:Oxygen / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism; D045332:Photosystem II Protein Complex; D013052:Spectrometry, X-Ray Emission; D018724:Spinacia oleracea / Q000737:chemistry / Q000378:metabolism
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D008345:Manganese; D007811:Lanthanum; D010100:Oxygen; D002118:Calcium