Evidence for N coordination to Fe in the (2Fe-2S) clusters of Thermus Rieske protein and phthalate dioxygenase from Pseudomonas
Rieske-type iron/sulfur proteins and several NADH-dependent oxygenases contain Fe/S clusters with similar spectral and magnetic properties. Purified Rieske iron/sulfur protein from Thermus thermophilus contains two apparently identical (2Fe-2S) clusters in a polypeptide having only four cysteine residues, and it has been proposed that each Fe/S cluster is coordinated to two cysteine S-atoms and to an unknown number of other non-sulfur atoms. The authors have examined the Rieske protein from Thermus and the phthalate dioxygenase from Pseudomonas cepacia with electron nuclear double resonance (ENDOR) and pulsed EPR methods and report here evidence for the direct coordination of nitrogenous ligands to the Fe/S clusters in these proteins. The electron nuclear double resonance signals arising from /sup 14/N have been interpreted in terms of a strongly coupled ligand with A/sup N/ = approx.26-28 MHz and a weakly coupled ligand with A/sup N/ = approx.9 MHz. The pulsed EPR spectrum shows a rich pattern of lines in the Fourier transformed data having peaks in the range of 0.8 to 6.7 MHz. The lower frequency resonances are tentatively associated with coupling of the unpaired spin to the remote N-atoms of coordinated imidazole rings. 26 references, 3 figures.
- Research Organization:
- Northwestern Univ., Evanston, IL
- OSTI ID:
- 5999756
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 260:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
OXYGENASES
MOLECULAR STRUCTURE
PROTEINS
BACTERIA
CYSTEINE
ELECTRON SPIN RESONANCE
IRON
LIGANDS
NADH2
NITROGEN 14
PHTHALATES
PSEUDOMONAS
SULFATES
AMINO ACIDS
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
COENZYMES
ELEMENTS
ENZYMES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
METALS
MICROORGANISMS
NITROGEN ISOTOPES
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
RESONANCE
STABLE ISOTOPES
SULFUR COMPOUNDS
THIOLS
TRANSITION ELEMENTS
550201* - Biochemistry- Tracer Techniques