Moessbauer spectroscopic study of the initial stages of iron-core formation in horse spleen apoferritin: Evidence for both isolated Fe(III) atoms and oxo-bridged Fe(III) dimers as early intermediates

Journal Article · Tue Jun 27 00:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00439a025· OSTI ID:5036839

Bauminger, E R; Nowik, I ^[1]; Harrison, P M; Treffry, A ^[2]

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1. Hebrew Univ., Jerusalem (Israel)
2. The Univ., Sheffield (England)

Ferritin stores iron within a hollow protein shell as a polynuclear Fe(III) hydrous oxide core. Although iron uptake into ferritin has been studied previously, the early stages in the creation of the core need to be clarified. These are dealt with in this paper by using Moessbauer spectroscopy, a technique that enables several types of Fe(II) and Fe(III) to be distinguished. Systematic Moessbauer studies were performed on samples prepared by adding {sup 57}Fe(II) atoms to apoferritin as a function of pH (5.6-7.0), n (the number of Fe/molecule (4-480)), and t{sub f} (the time the samples were held at room temperature before freezing). Four different Fe(III) species were identified: solitary Fe(III) atoms giving relaxation spectra, which can be identified with the species observed before by EPR and UV difference spectroscopy; oxo-bridged dimers giving doublet spectra with large splitting, observed for the first time in ferritin; small Fe(III) clusters giving doublets of smaller splitting and larger antiferromagnetically coupled Fe(III) clusters, similar to those found previously in larger ferritin iron cores, which, for samples with n {ge} 40, gave magnetically split spectra at 4.1 K. Both solitary Fe(III) and dimers diminished with time, suggesting that they are intermediates in the formation of the iron core. Two kinds of divalent iron were distinguished for n = 480, which may correspond to bound and free Fe(II).

• OSTI ID: 5036839
• Journal Information: Biochemistry; (USA), Vol. 28:13; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
IRON 57
UPTAKE
METALLOPROTEINS
SPECTROSCOPY
COBALT 57
ELECTRON SPIN RESONANCE
FERRITIN
HORSES
IRON 56
PH VALUE
SPLEEN
ULTRAVIOLET SPECTRA
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
COBALT ISOTOPES
COMPLEXES
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
IRON COMPLEXES
IRON ISOTOPES
ISOTOPES
MAGNETIC RESONANCE
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RESONANCE
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques