Multinuclear magnetic resonance studies of the 2Fe-2S sup * ferredoxin from Anabaena species strain PCC 7120. 3. Detection and characterization of hyperfine-shifted nitrogen-15 and hydrogen-1 resonances of the oxidized form

Journal Article · Tue Apr 24 00:00:00 EDT 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00468a031· OSTI ID:6274215

Oh, Byung-Ha; Markley, J L ^[1]

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1. Univ. of Wisconsin, Madison (USA)

All the nitrogen signals from the amino acid side chains and 80 of the total of 98 backbone nitrogen signals of the oxidized form of the 2Fe{center dot}2S* ferredoxin from Anabaena sp. strain PCC 7120 were assigned by means of a series of heteronuclear two-dimensional experiments. Two additional nitrogen signals were observed in the one-dimensional {sup 15}N NMR spectrum and classified as backbone amide resonances from residues whose proton resonances experience paramagnetic broadening. The one-dimensional {sup 15}N NMR spectrum shows nine resonances that are hyperfine shifted and broadened. From this inventory of diamagnetic nitrogen signals and the available X-ray coordinates of the related ferredoxin, the resolved hyperfine-shifted {sup 15}N peaks were attributed to backbone amide nitrogens of two other amino acids that share electrons with the 2Fe{center dot}2S* center to backbone amide nitrogens of two other amino acids that are close to the 2Fe{center dot}2S* center. The seven {sup 15}N signals that are missing and unaccounted for probably are buried under the envelope of amide signals. {sup 1}H NMR signals from all the amide protons directly bonded to the seven missing and nine hyperfine-shifted nitrogens were too broad to be resolved in conventional 2D NMR spectra. From their dependence on the magnetogyric ratio, a {sup 1}H resonance should be up to 100 times broader than a {sup 15}N resonance that experiences a similar hyperfine interaction. This appears to be the reason why more well-resolved hyperfine-shifted {sup 15}N resonances were observed than corresponding {sup 1}H resonances. The result suggest that hyperfine-shifted {sup 15}N peaks can provide a unique window on the electronic structure and environment of this and other paramagnetic centers.

• OSTI ID: 6274215
• Journal Information: Biochemistry; (USA), Vol. 29:16; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CYANOBACTERIA
MOLECULAR BIOLOGY
FERREDOXIN
NUCLEAR MAGNETIC RESONANCE
CHEMICAL SHIFT
HYPERFINE STRUCTURE
IRON COMPLEXES
NITROGEN 15
NMR SPECTRA
OXIDATION
PROTONS
SULFUR COMPLEXES
BARYONS
CHEMICAL REACTIONS
COMPLEXES
ELEMENTARY PARTICLES
FERMIONS
HADRONS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
METALLOPROTEINS
MICROORGANISMS
NITROGEN ISOTOPES
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RESONANCE
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES
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