Identification of the iron entry channels in apoferritin. Chemical modification and spectroscopic studies

Journal Article · Tue Jan 10 00:00:00 EST 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00427a052· OSTI ID:5404067

Stefanini, S; Desideri, A; Vecchini, P; Drakenberg, T; Chiancone, E ^[1]

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1. Univ. of Rome, La Sapienza (Italy)

The knowledge of the route through which iron can enter and leave the apoferritin shell is a prerequisite for the understanding of ferritin's function. The involvement of the hydrophilic 3-fold channels in the iron uptake process has been studied by taking advantage of the reactivity of specific residues that line such channels, i.e., glutamic acid-127 and aspartic acid-130, the major Cd(II) binding sites, and cysteine-126. {sup 113}Cd NMR experiments have provided direct evidence for the competition between Fe(II) and Cd(II) binding to major Cd(II) binding sites on the protein and for a higher affinity of Fe(II) for these sites, in line with the well-known inhibitory effect of Cd(II) on iron uptake. Further evidence for the use of the 3-fold channels in the iron entry process has been obtained by means of chemical modification of Cys-126 with different mercurials. In particular, the introduction of the additional carboxylate carried by p-(chloromercuri)benzoate near Asp-127 and Glu-130 increases the initial rate of iron uptake and affects the coordination geometry of the metal in the Fe(III)-apoferritin complex as indicated by optical absorption and EPR data. The assignment of these effects to the carboxylate moiety of p-(choloromercuri)benzoate is brought out by the observation that the introduction in the 3-fold channel of the benzene ring only by means of phenylmercuric acetate has no effect on the initial iron uptake kinetics and on the spectroscopic properties of the Fe(III)-apoferritin complex.

• OSTI ID: 5404067
• Journal Information: Biochemistry; (USA), Vol. 28:1; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CADMIUM 113
UPTAKE
FERRITIN
NUCLEAR MAGNETIC RESONANCE
ASPARTIC ACID
CATIONS
CYSTEINE
ELECTRON SPIN RESONANCE
GLUTAMIC ACID
IRON COMPOUNDS
MOLECULAR STRUCTURE
AMINO ACIDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CADMIUM ISOTOPES
CARBOXYLIC ACIDS
CHARGED PARTICLES
COMPLEXES
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
IONS
IRON COMPLEXES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MAGNETIC RESONANCE
METALLOPROTEINS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PROTEINS
RADIOISOTOPES
RESONANCE
STABLE ISOTOPES
THIOLS
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
YEARS LIVING RADIOISOTOPES
550601* - Medicine- Unsealed Radionuclides in Diagnostics