Functional Analysis of the Iron(II) Etiocorrphycene Incorporated in the Myoglobin Heme Pocket

• Published in: Chemical & pharmaceutical bulletin Vol. 49; no. 3; pp. 345 - 346
• Main Authors: NEYA, Saburo, NAKAMURA, Mihoko, IMAI, Kiyohiro, FUNASAKI, Noriaki
• Format: Journal Article
• Language: English
• Published: Tokyo The Pharmaceutical Society of Japan 2001; Maruzen; Japan Science and Technology Agency
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; deformed coordination core; Fundamental and applied biological sciences. Psychology; Heme - chemistry; Hemoproteins; Indicators and Reagents; iron(II) corrphycene; Metalloporphyrins - chemistry; Metalloproteins; Myoglobin - chemistry; Oxygen - chemistry; oxygen binding; Proteins; reconstituted myoglobin; Spectrophotometry, Infrared; Iron II Complexes; Myoglobin; Divalent metal Complexes; Absorption spectrometry; Hemoprotein; Organic ligand; Visible spectrometry; Oxygen affinity; Isomer; Macrocycle
• ISSN: 0009-2363; 1347-5223
• DOI: 10.1248/cpb.49.345

The iron(II) complex of 2, 7, 12, 17-tetraethyl-3, 6, 11, 18-tetramethylcorrphycene, an isomeric heme, was complexed with apomyoglobin to examine the ligand binding ability of the novel macrocycle under physiological conditions. The reconstituted holoprotein was found to be functionally active at pH 7.4 and 20 °C and to bind oxygen and carbon monoxide reversibly with a half-saturation pressure at 6.7 and 3.5 mmHg, respectively. Equilibrium affinities for these ligands are one to two orders of magnitude lower than those reported for native myoglobin. The functional anomaly was ascribed to the geometric and electronic strain on the iron(II) atom in the trapezoidal coordination core of corrphycene.