Ligand binding properties of myoglobin reconstituted with iron porphycene

Unusual O2 binding selectivity against CO binding

Takashi Matsuo, Hjrohisa Dejima, Shun Hirota, Dai Murata, Hideaki Sato, Takahiro Ikegami, Hiroshi Hori, Yoshio Hisaeda, Takashi Hayashi

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

Sperm whale myoglobin, an oxygen storage hemoprotein, was successfully reconstituted with the iron porphycene having two propionates, 2,7-diethyl-3,6,12,17-tetramethyl-13,16-bis(carboxyethyl)-porphycenatoiron. The physicochemical properties and ligand bindings of the reconstituted myoglobin were investigated. The ferric reconstituted myoglobin shows the remarkable stability against acid denaturation and only a low-spin characteristic in its EPR spectrum. The Fe(III)/Fe(II) redox potential (-190 mV vs NHE) determined by the spectroelectrochemical measurements was much lower than that of the wild-type. These results can be attributed to the strong coordination of His93 to the porphycene iron, which is induced by the nature of the porphycene ring symmetry. The O2 affinity of the ferrous reconstituted myoglobin is 2600-fold higher than that of the wild-type, mainly due to the decrease in the O2 dissociation rate, whereas the CO affinity is not so significantly enhanced. As a result, the O2 affinity of the reconstituted myoglobin exceeds its CO affinity (M = KCO/KO2 < 1). The ligand binding studies on H64A mutants support the fact that the slow O 2 dissociation of the reconstituted myoglobin is primarily caused by the stabilization of the Fe-O2 σ-bonding. The IR spectra for the carbon monoxide (CO) complex of the reconstituted myoglobin suggest several structural and/or electrostatic conformations of the Fe-C-O bond, but this is not directly correlated with the CO dissociation rate. The high O2 affinity and the unique characteristics of the myoglobin with the iron porphycene indicate that reconstitution with a synthesized heme is a useful method not only to understand the physiological function of myoglobin but also to create a tailor-made function on the protein.

Original languageEnglish
Pages (from-to)16007-16017
Number of pages11
JournalJournal of the American Chemical Society
Volume126
Issue number49
DOIs
Publication statusPublished - Dec 15 2004

Fingerprint

Myoglobin
Carbon Monoxide
Carbon monoxide
Iron
Ligands
Denaturation
Paramagnetic resonance
Conformations
Electrostatics
Stabilization
Proteins
Sperm Whale
Oxygen
Acids
porphycene
Propionates
Static Electricity
Heme
Oxidation-Reduction

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Ligand binding properties of myoglobin reconstituted with iron porphycene : Unusual O2 binding selectivity against CO binding. / Matsuo, Takashi; Dejima, Hjrohisa; Hirota, Shun; Murata, Dai; Sato, Hideaki; Ikegami, Takahiro; Hori, Hiroshi; Hisaeda, Yoshio; Hayashi, Takashi.

In: Journal of the American Chemical Society, Vol. 126, No. 49, 15.12.2004, p. 16007-16017.

Research output: Contribution to journalArticle

Matsuo, Takashi ; Dejima, Hjrohisa ; Hirota, Shun ; Murata, Dai ; Sato, Hideaki ; Ikegami, Takahiro ; Hori, Hiroshi ; Hisaeda, Yoshio ; Hayashi, Takashi. / Ligand binding properties of myoglobin reconstituted with iron porphycene : Unusual O2 binding selectivity against CO binding. In: Journal of the American Chemical Society. 2004 ; Vol. 126, No. 49. pp. 16007-16017.
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abstract = "Sperm whale myoglobin, an oxygen storage hemoprotein, was successfully reconstituted with the iron porphycene having two propionates, 2,7-diethyl-3,6,12,17-tetramethyl-13,16-bis(carboxyethyl)-porphycenatoiron. The physicochemical properties and ligand bindings of the reconstituted myoglobin were investigated. The ferric reconstituted myoglobin shows the remarkable stability against acid denaturation and only a low-spin characteristic in its EPR spectrum. The Fe(III)/Fe(II) redox potential (-190 mV vs NHE) determined by the spectroelectrochemical measurements was much lower than that of the wild-type. These results can be attributed to the strong coordination of His93 to the porphycene iron, which is induced by the nature of the porphycene ring symmetry. The O2 affinity of the ferrous reconstituted myoglobin is 2600-fold higher than that of the wild-type, mainly due to the decrease in the O2 dissociation rate, whereas the CO affinity is not so significantly enhanced. As a result, the O2 affinity of the reconstituted myoglobin exceeds its CO affinity (M = KCO/KO2 < 1). The ligand binding studies on H64A mutants support the fact that the slow O 2 dissociation of the reconstituted myoglobin is primarily caused by the stabilization of the Fe-O2 σ-bonding. The IR spectra for the carbon monoxide (CO) complex of the reconstituted myoglobin suggest several structural and/or electrostatic conformations of the Fe-C-O bond, but this is not directly correlated with the CO dissociation rate. The high O2 affinity and the unique characteristics of the myoglobin with the iron porphycene indicate that reconstitution with a synthesized heme is a useful method not only to understand the physiological function of myoglobin but also to create a tailor-made function on the protein.",
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T1 - Ligand binding properties of myoglobin reconstituted with iron porphycene

T2 - Unusual O2 binding selectivity against CO binding

AU - Matsuo, Takashi

AU - Dejima, Hjrohisa

AU - Hirota, Shun

AU - Murata, Dai

AU - Sato, Hideaki

AU - Ikegami, Takahiro

AU - Hori, Hiroshi

AU - Hisaeda, Yoshio

AU - Hayashi, Takashi

PY - 2004/12/15

Y1 - 2004/12/15

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