Axial coordination of ferric Aplysia myoglobin.

Denis L. Rousseau, Y. C. Ching, M. Brunori, G. M. Giacometti

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Resonance Raman spectra of ferric Aplysia myoglobin in the ligand-free and the azide-bound forms have been studied over a wide pH range to determine the coordination states of the heme iron atom. In the hydroxide form at high pH (approximately 9) the iron is six-coordinate and is in a high/low spin equilibrium. As the pH is lowered below the acid/alkaline transition (pKa = 7.5), the heme becomes five-coordinate. When the pH is lowered even further no other changes in the resonance Raman spectrum are detected; thus, the heme remains five-coordinate down to pH 4, the lowest value studied. For ferric azide-bound Aplysia myoglobin, the iron is six-coordinate in a high/low spin equilibrium at all pH values (4.8-9). These data indicate (i) that the unusual reactivity toward azide previously observed at neutral pH is indeed related to the absence of a coordinated water molecule, and (ii) that causes other than the heme coordination are responsible for the spectral differences and the ligand-binding kinetics differences observed below pH 6.

Original languageEnglish (US)
Pages (from-to)7878-7881
Number of pages4
JournalJournal of Biological Chemistry
Volume264
Issue number14
StatePublished - May 15 1989
Externally publishedYes

Fingerprint

Aplysia
Myoglobin
Heme
Azides
Iron
Raman scattering
Ligands
Atoms
Molecules
Kinetics
Acids
Water

ASJC Scopus subject areas

  • Biochemistry

Cite this

Rousseau, D. L., Ching, Y. C., Brunori, M., & Giacometti, G. M. (1989). Axial coordination of ferric Aplysia myoglobin. Journal of Biological Chemistry, 264(14), 7878-7881.

Axial coordination of ferric Aplysia myoglobin. / Rousseau, Denis L.; Ching, Y. C.; Brunori, M.; Giacometti, G. M.

In: Journal of Biological Chemistry, Vol. 264, No. 14, 15.05.1989, p. 7878-7881.

Research output: Contribution to journalArticle

Rousseau, DL, Ching, YC, Brunori, M & Giacometti, GM 1989, 'Axial coordination of ferric Aplysia myoglobin.', Journal of Biological Chemistry, vol. 264, no. 14, pp. 7878-7881.
Rousseau DL, Ching YC, Brunori M, Giacometti GM. Axial coordination of ferric Aplysia myoglobin. Journal of Biological Chemistry. 1989 May 15;264(14):7878-7881.
Rousseau, Denis L. ; Ching, Y. C. ; Brunori, M. ; Giacometti, G. M. / Axial coordination of ferric Aplysia myoglobin. In: Journal of Biological Chemistry. 1989 ; Vol. 264, No. 14. pp. 7878-7881.
@article{d4b222c2e3ff4847b97787ccac42f834,
title = "Axial coordination of ferric Aplysia myoglobin.",
abstract = "Resonance Raman spectra of ferric Aplysia myoglobin in the ligand-free and the azide-bound forms have been studied over a wide pH range to determine the coordination states of the heme iron atom. In the hydroxide form at high pH (approximately 9) the iron is six-coordinate and is in a high/low spin equilibrium. As the pH is lowered below the acid/alkaline transition (pKa = 7.5), the heme becomes five-coordinate. When the pH is lowered even further no other changes in the resonance Raman spectrum are detected; thus, the heme remains five-coordinate down to pH 4, the lowest value studied. For ferric azide-bound Aplysia myoglobin, the iron is six-coordinate in a high/low spin equilibrium at all pH values (4.8-9). These data indicate (i) that the unusual reactivity toward azide previously observed at neutral pH is indeed related to the absence of a coordinated water molecule, and (ii) that causes other than the heme coordination are responsible for the spectral differences and the ligand-binding kinetics differences observed below pH 6.",
author = "Rousseau, {Denis L.} and Ching, {Y. C.} and M. Brunori and Giacometti, {G. M.}",
year = "1989",
month = "5",
day = "15",
language = "English (US)",
volume = "264",
pages = "7878--7881",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "14",

}

TY - JOUR

T1 - Axial coordination of ferric Aplysia myoglobin.

AU - Rousseau, Denis L.

AU - Ching, Y. C.

AU - Brunori, M.

AU - Giacometti, G. M.

PY - 1989/5/15

Y1 - 1989/5/15

N2 - Resonance Raman spectra of ferric Aplysia myoglobin in the ligand-free and the azide-bound forms have been studied over a wide pH range to determine the coordination states of the heme iron atom. In the hydroxide form at high pH (approximately 9) the iron is six-coordinate and is in a high/low spin equilibrium. As the pH is lowered below the acid/alkaline transition (pKa = 7.5), the heme becomes five-coordinate. When the pH is lowered even further no other changes in the resonance Raman spectrum are detected; thus, the heme remains five-coordinate down to pH 4, the lowest value studied. For ferric azide-bound Aplysia myoglobin, the iron is six-coordinate in a high/low spin equilibrium at all pH values (4.8-9). These data indicate (i) that the unusual reactivity toward azide previously observed at neutral pH is indeed related to the absence of a coordinated water molecule, and (ii) that causes other than the heme coordination are responsible for the spectral differences and the ligand-binding kinetics differences observed below pH 6.

AB - Resonance Raman spectra of ferric Aplysia myoglobin in the ligand-free and the azide-bound forms have been studied over a wide pH range to determine the coordination states of the heme iron atom. In the hydroxide form at high pH (approximately 9) the iron is six-coordinate and is in a high/low spin equilibrium. As the pH is lowered below the acid/alkaline transition (pKa = 7.5), the heme becomes five-coordinate. When the pH is lowered even further no other changes in the resonance Raman spectrum are detected; thus, the heme remains five-coordinate down to pH 4, the lowest value studied. For ferric azide-bound Aplysia myoglobin, the iron is six-coordinate in a high/low spin equilibrium at all pH values (4.8-9). These data indicate (i) that the unusual reactivity toward azide previously observed at neutral pH is indeed related to the absence of a coordinated water molecule, and (ii) that causes other than the heme coordination are responsible for the spectral differences and the ligand-binding kinetics differences observed below pH 6.

UR - http://www.scopus.com/inward/record.url?scp=0024970361&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0024970361&partnerID=8YFLogxK

M3 - Article

VL - 264

SP - 7878

EP - 7881

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 14

ER -