Nitrogen ligation to manganese in the photosynthetic oxygen-evolving complex: Continuous-wave and pulsed EPR studies of Photosystem II particles containing sup 14 N or sup 15 N

Journal Article · Tue Feb 05 04:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00219a025· OSTI ID:5394261

DeRose, V J; Yachandra, V K; McDermott, A E; Britt, R D; Sauer, K; Klein, M P ^[1]

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1. Univ. of California, Berkeley (USA)

The possibility of nitrogen ligation to the Mn in the oxygen-evolving complex from photosystem II was investigated with electron paramagnetic resonance (EPR) and electron spin echo envelope modulation (ESEEM) spectroscopies using {sup 14}N- and {sup 15}N-labeled preparations. Oxygen-evolving preparations were isolated from a thermophilic cyanobacterium, Synechococcus sp., grown on a medium containing either {sup 14}NO{sub 3{sup {minus}}} or {sup 15}NO{sup {minus}}{sub 3} as the sole source of nitrogen. The substructure on the multiline EPR signal, which arises from Mn in the S{sub 2} state of the enzyme, was measured with continuous-wave EPR. No changes were detected in the substructure peak positions upon substitution of {sup 15}N for {sup 14}N, indicating that this substructure is not due to superhyperfine coupling from nitrogen ligands. To detect potential nitrogen ligands with superhyperfine couplings of lesser magnitude than could be observed with conventional EPR methods, electron spin-echo envelope modulation experiments were also performed on the multiline EPR signal. The Fourier transform of the light-minus-dark time domain ESEEM data shows a peak at 4.8 MHz in {sup 14}N samples which is absent upon substitution with {sup 15}N. This gives unambiguous evidence for weak hyperfine coupling of nitrogen to the Mn of the oxygen-evolving complex. Possible origins of this nitrogen interaction are discussed.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5394261
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 30:5; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
CHEMICAL REACTIONS
CYANOBACTERIA
ELECTRON SPIN RESONANCE
FOURIER ANALYSIS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MANGANESE COMPOUNDS
MICROORGANISMS
NITRATES
NITROGEN 14
NITROGEN 15
NITROGEN COMPOUNDS
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHOTOSYNTHETIC REACTION CENTERS
RESONANCE
STABLE ISOTOPES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS