Electron spin echo envelope modulation spectroscopy supports the suggested coordination of two histidine ligands to the Rieske Fe-S centers of the cytochrome b sub 6 f complex of spinach and the cytochrome bc sub 1 complexes of Rhodospirillum rubrum, Rhodobacter sphaeroides R-26, and bovine heart mitochondria

Journal Article · Tue Feb 19 00:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00221a023· OSTI ID:5596146

Britt, R D; Sauer, K; Klein, M P ^[1]; Knaff, D B; Kriauciunas, A ^[2]; Yu, Changan; Yu, Linda ^[3]; Malkin, R ^[4]

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1. Lawrence Berkeley Lab., CA (USA)
2. Texas Tech Univ., Lubbock (USA)
3. Oklahoma State Univ., Stillwater (USA)
4. Univ. of California, Berkeley (USA)

Electron spin echo envelope modulation (ESEEM) experiments performed on the Rieske Fe-S clusters of the cytochrome b{sub 6}f complex of spinach chloroplasts and of the cytochrome bc{sub 1} complexes of Rhodospirillum rubrum, Rhodobacter sphaeroides R-26, and bovine heart mitochondria show modulation components resulting from two distinct classes of {sup 14}N ligands. At the g = 1.92 region of the Rieske EPR spectrum of the cytochrome b{sub 6}f complex, the measured hyperfine couplings for the two classes of coupled nitrogens are A{sub 1} = 4.6 MHz and A{sub 2} = 3.8 MHz. Similar couplings are observed for the Rieske centers in the three cytochrome bc{sub 1} complexes. These ESEEM results indicate a nitrogen coordination environment for these Rieske Fe-S centers that is similar to that of the Fe-S cluster of a bacterial dioxygenase enzyme with two coordinated histidine ligands. The Rieske Fe-S cluster lacks modulation components from a weakly coupled peptide nitrogen observed in water-soluble spinach ferredoxin. Treatment with the quinone analogue inhibitor DBMIB causes a shift in the Rieske EPR spectrum to g = 1.95 with no alteration in the magnetic couplings to the two nitrogen atoms. However, the ESEEM pattern of the DBMIB-altered Rieske EPR signal shows evidence of an additional weakly coupled nitrogen similar to that observed in the spinach ferrodoxin ESEEM patterns.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5596146
• Journal Information: Biochemistry; (United States), Vol. 30:7; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CYTOCHROMES
HYPERFINE STRUCTURE
CATTLE
CHLOROPLASTS
ELECTRON SPIN RESONANCE
HEART
HISTIDINE
LIGANDS
MITOCHONDRIA
NITROGEN 14
PHOTOSYNTHESIS
PROTEINS
RHODOSPIRILLUM
SPINACH
AMINO ACIDS
ANIMALS
AZOLES
BACTERIA
BODY
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CHEMICAL REACTIONS
DOMESTIC ANIMALS
FOOD
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
IMIDAZOLES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MAMMALS
MICROORGANISMS
NITROGEN ISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PHOTOCHEMICAL REACTIONS
PIGMENTS
PLANTS
RESONANCE
RUMINANTS
STABLE ISOTOPES
SYNTHESIS
VEGETABLES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques