Assignments of sup 15 N and sup 1 H NMR resonances and a neutral pH ionization in Rhodospirillum rubrum cytochrome c sub 2
- Univ. of California, Davis (USA)
The {pi}NH proton and {sup 15}N resonances of the ligand histidine of Rhodospirillum rubrum ferricytochrome c{sub 2} are found at 14.7 and 184 ppm, respectively, contradicting the proposal that this proton is absent in the R. rubrum ferricytochrome. Substitution of the deuterium atom for this proton causes small upfield shifts of the {pi} nitrogen in both oxidation states, indicating that the {pi}NH-peptide carboxyl hydrogen bond is not substantially weakened by the substitution. The proton and {sup 15}N resonances of the indolic NH group of the invariant tryptophan-62 and numerous proton resonances of the heme and extraheme ligands in the spectrum of the ferricytochrome are also assigned. An ionization in the ferrocytochrome occurring at neutral pH is assigned to the single nonligand histidine. This attribution is supported by the direct measurement of the ionization by NOE difference spectroscopy and by comparative structural arguments involving closely related cytochromes and chemically modified cytochromes.
- OSTI ID:
- 6277619
- Journal Information:
- Biochemistry; (USA), Vol. 29:12; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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CYTOCHROMES
MOLECULAR STRUCTURE
HEME
NUCLEAR MAGNETIC RESONANCE
LIGANDS
AMMONIUM CHLORIDES
CHEMICAL SHIFT
HEAVY WATER
HISTIDINE
IONIZATION
METHIONINE
NITROGEN 15
OXIDATION
PH VALUE
PROTONS
RHODOSPIRILLUM
AMINO ACIDS
AMMONIUM COMPOUNDS
AMMONIUM HALIDES
AZOLES
BACTERIA
BARYONS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
DRUGS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
IMIDAZOLES
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAGNETIC RESONANCE
MICROORGANISMS
NITROGEN ISOTOPES
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
PIGMENTS
PORPHYRINS
PROTEINS
RESONANCE
STABLE ISOTOPES
WATER
550201* - Biochemistry- Tracer Techniques