The S sub 0 state of photosystem II induced by hydroxylamine: Differences between the structure of the manganese complex in the S sub 0 and S sub 1 states determined by X-ray absorption spectroscopy

Journal Article · Tue Jan 16 04:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00454a024· OSTI ID:6696604

Guiles, R D; Yachandra, V K; McDermott, A E; Cole, J L; Dexheimer, S L; Britt, R D; Sauer, K; Klein, M P ^[1]

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1. Lawrence Berkeley Lab., CA (USA)

Hydroxylamine at low concentrations causes a two-flash delay in the first delay in the first maximum flash yield oxygen evolved from spinach photosystem II (PSII) subchloroplast membranes that have been excited by a series of saturating flashes of light. Untreated PSII membrane preparations exhibit a multiline EPR signal assigned to a manganese cluster and associated with the S{sub 2} state when illuminated at 195 K, or at 273 K in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). The authors used the extent of suppression of the multiline EPR signal observed in samples illuminated at 195 K to determine the fraction of PSII reaction centers set back to a hydroxylamine-induced S{sub 0}-like state, which they designate S{sub 0}. The manganese K-edge X-ray absorption edges for dark-adapted PSII preparations with or without hydroxylamine are virtually identical. This indicates that, despite its high binding affinity to the oxygen-evolving complex (OEC) in the dark, hydroxylamine does not reduce chemically the manganese cluster within the OEC in the dark. After a single turnover of PSII a shift to lower energy is observed in the inflection of the Mn K-edge of the manganese cluster. They conclude that, in the presence of hydroxylamine, illumination causes a reduction of the OEC, resulting in a state resembling S{sub 0}. This lower Mn K-edge energy of S{sub 0}, relative to the edge of S{sub 1}, implies that storage and stabilization of an oxidative equivalent within the manganese cluster during the S{sub 0} {yields} S{sub 1} state transition. An analysis of the extended X-ray absorption fine structure (EXAFS) of the S{sub 0} state indicates that a significant structural rearrangement occurs between the S{sub 0} and S{sub 1} states.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6696604
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:2; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550602* -- Medicine-- External Radiation in Diagnostics-- (1980-)
62 RADIOLOGY AND NUCLEAR MEDICINE
ABSORPTION SPECTROSCOPY
AMIDES
AMINES
BIOLOGICAL EFFECTS
CARBONIC ACID DERIVATIVES
CHEMICAL REACTIONS
COMPLEXES
ELECTRON SPIN RESONANCE
FINE STRUCTURE
FOOD
HYDROGEN COMPOUNDS
HYDROXYLAMINE
MAGNETIC RESONANCE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MANGANESE COMPLEXES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
PHOTOSYNTHETIC REACTION CENTERS
PLANTS
RESONANCE
SPECTROSCOPY
SPINACH
TRANSITION ELEMENT COMPLEXES
UREA
VEGETABLES
WATER
X-RAY SPECTROSCOPY