Structural Studies of Manganese and Halide in the Photosynthetic Oxygen Evolving Complex [Thesis]

Technical Report · Mon Oct 01 04:00:00 EDT 1990

DOI:https://doi.org/10.2172/6079089· OSTI ID:6079089

DeRose, Victoria Jeanne ^[1]

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1. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Electron paramagnetic resonance (EPR) and x-ray absorption spectroscopy (XAS) were used as probes of the manganese atoms of the oxygen evolving complex (OEC). XAS studies at liquid helium temperatures allowed the observation of a scatterer at >3 Å from the absorbing manganese. Extended x-ray absorption fine structure (EXAFS) data taken on preparations from both spinach and the thermophilic cyanobacterium Synechococcus sp. fit to nearly identical parameters. By comparison with model compounds the scatterer at >3 Å fits well to a single manganese-manganese distance per the four manganese in the OEC cluster. The correlation between fluoride inhibition of oxygen evolution activity and enhancement of the g = 4 EPR signal which arises from the OEC in the S₂ state was ascertained. The narrowing of the EPR signal is interpreted as being due to fluoride binding to the manganese. A damping of the scattering due to manganese at 2.7 Å was observed in data from the fluoride-treated preparations poised in the S₂ state. EXAFS of bromide-substituted PSII preparations from Synechococcus showed no change relative to EXAFS of chloride-containing samples. The substructure observed by high resolution EPR of the S₂-state multiline signal also shows no change in the presence of bromide. These results argue strongly against the presence of a halide ligand bridging the manganese in the OEC, but do not exclude a single terminal halide ligand. Electron spin echo spectroscopy of ¹⁵N-containing preparations from Synechococcus identify nuclear envelope modulation due to nitrogen near the manganese of the OEC. The modulation frequency is consistent with its arising from an amino acid ligand such as a histidine.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source
• Sponsoring Organization: USDOE Office of Energy Research (ER); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); National Institutes of Health (NIH)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6079089
• Report Number(s): LBL--30077; ON: DE91009071; CNN: DMB 88-04526
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ACOUSTIC ESR
AMINO ACIDS
AZOLES
BOND LENGTHS
BROMIDES
BROMINE COMPOUNDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CLEAVAGE
COMPLEXES
CRYSTAL STRUCTURE
CYANOBACTERIA
DIMENSIONS
ELECTRON SPIN RESONANCE
ELEMENTS
FLUORIDES
FLUORINE COMPOUNDS
FOOD
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
IMIDAZOLES
LENGTH
LIGANDS
MAGNETIC RESONANCE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MANGANESE COMPLEXES
MEMBRANES
MICROORGANISMS
MICROSTRUCTURE
MOLECULAR STRUCTURE
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHOTOSYNTHETIC BACTERIA
PHOTOSYNTHETIC MEMBRANES
PLANTS
PRODUCTION
PROTEINS
RESONANCE
SPECTROSCOPY
SPINACH
STRUCTURAL MODELS
STRUCTURE-ACTIVITY RELATIONSHIPS
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
VEGETABLES
X-RAY SPECTROSCOPY