title: Comparison of the structure of the manganese complex in the S1 and S2 states of the photosynthetic O2-evolving complex: an x-ray absorption spectroscopy study.
abstract: A Mn-containing enzyme complex is involved in the oxidation of H2O to O2 in algae and higher plants. X-ray absorption spectroscopy is well suited for studying the structure and function of Mn in this enzyme complex. Results of X-ray K-edge and extended X-ray absorption fine structure (EXAFS) studies of Mn in the S1 and S2 states of the photosynthetic O2-evolving complex in photosystem II preparations from spinach are presented in this paper. The S2 state was prepared by illumination at 190 K or by illumination at 277 K in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU); these are protocols that limit the photosystem II reaction center to one turnover. Both methods produce an S2 state characterized by a multiline electron paramagnetic resonance (EPR) signal. An additional protocol, illumination at 140 K, produces as a state characterized by the g = 4.1 EPR signal. We have previously observed a shift to higher energy in the X-ray absorption K-edge energy of Mn upon advancement from the dark-adapted S1 state to the S2 state produced by illumination at 190 K [Goodin, D. B., Yachandra, V. K., Britt, R. D., Sauer, K., & Klein, M. P. (1984) Biochim. Biophys. Acta 767, 209-216]. The Mn K-edge spectrum of the 277 K illuminated sample is similar to that produced at 190 K, indicating that the S2 state is similar when produced at 190 or 277 K.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Laboratory of Chemical Biodynamics, Lawrence Berkeley Laboratory, University of California, Berkeley 94720.
authors.forename: V K
authors.initials: VK
authors.lastname: Yachandra
authors.forename: R D
authors.initials: RD
authors.lastname: Guiles
authors.forename: A E
authors.initials: AE
authors.lastname: McDermott
authors.forename: J L
authors.initials: JL
authors.lastname: Cole
authors.forename: R D
authors.initials: RD
authors.lastname: Britt
authors.forename: S L
authors.initials: SL
authors.lastname: Dexheimer
authors.forename: K
authors.initials: K
authors.lastname: Sauer
authors.forename: M P
authors.initials: MP
authors.lastname: Klein
mesh_terms: D002734:Chlorophyll / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D045342:Light-Harvesting Protein Complexes; D008345:Manganese / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000378:metabolism; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D002734:Chlorophyll; D008345:Manganese; D010100:Oxygen