1997 Fiscal Year Final Research Report Summary
Molecular mechanism of heme degradation catalyzed by heme oxygenase
| Project/Area Number |
08044240
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
Structural biochemistry
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| Research Institution | YAMAGATA UNIVERSITY |
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Principal Investigator |
YOSHIDA Tadashi YAMAGATA UNIVERSITY SCHOOL OF MEDICINE,DEPARTMENT OF BIOCHEMISTRY,PROFESSOR, 医学部, 教授 (10004673)
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| Co-Investigator(Kenkyū-buntansha) |
周 虹 ハルビン医科大学, 講師
OLSON John S. RICE UNIVERSITY,DEPARTMENT OF PHYSIOLOGY AND BIOPHYSICS,PROFESSOR, 教授
IKEDA-SAITO Masao CASE WESTERN RESERVE UNIVERSITY SCHOOL OF MEDICINE,DEPARTMENT OF PHYSIOLOSY AND, 教授
MIGITA Taiko YAMAGUCHI UNIVERSITY SCHOOL OF ALLIED HEALTH SCIENCES,ASSOCIATE PROFESSOR, 医療技術短期大学部, 助教授 (90159161)
FUJII Hiroshi YAMAGATA TECHNOPOLIS FOUNDATION,THE INSTITUTE FOR LIFE SUPPORT TECHNOLOGY,CHIEF, 生物ラジカル研究所, 主任研究員 (80228957)
ZHOU Hong HARBIN PRECLINICAL COLLEGE OF MEDICINE OF MEDICAL UNIVERSITY,ASSISTANT PROFESSOR
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| Project Period (FY) |
1996 – 1997
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| Keywords | Heme oxygenase / Oxygenase / O_2 activation mechanism / Heme / Degradation of heme / CO / Bieiverdin / Bilirubin |
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| Research Abstract |
(1) We observed the resonance Raman spectra for alpha-hydroxyheme and verdoheme complexes of heme oxygensae (HO). We found that the ferric alpha-hydroxyheme and ferrous verdoheme complexes showed atypical Raman patterns, which are interpreted. as the result of the symmnetry lowering of the porphyrin-conjugating pi-electron system.
(2) previously we found that histidine residue of HO was the proximal lignd of heme. To identify the axial heme lignd of HO-2, we prepared His45 to Ala (H45A) and His152 to Ala (H152A) mutants. H45A could form a 1 : 1 complex with hemin but was completely devoid of the heme degradation activity. A 5-coordinate-type ferrous NO EPR spectrum was observed for the heme-H45A complex. On the contrary, H152A mutant exhibited spectroscopic and enzymatic properties identical to those of wild-type. His132 of HO-1, Which corresponds to His152 of HO-2, was also not important for the heme degradation activity.
(3) The O_2 and CO reactions with the heme, alpha-hydroxyheme, and veroheme complexes of HO were studied. The heme complexs of HO-1 and HO-2 have similar O_2 and CO binding properties. The O_2 affinities for heme and hydroxyheme・are very high, but the CO affinities are only 1-6-fold higher than the O_2 affinities. Thus, HO discriminate much more strongly against CO binding than myoglobin. The CO affinities of the verdoheme complex are about 10,000 times weaker than those of the heme complex. The positive charge on the verdoporphyrin ring causes a large decrease in reactivity of the iron.
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[Publications] Ikeda-Saito, Masao.et al.: Heme oxygenase : a central enzyme of oxygen-dependent heme catabolism and carbon monoxide synthesis.In Oxygen Homeostasis and Its Dynamics (Ishimura, Y., Shimada, H., and Suematu, M., eds), Spring-Verlag, Tokyo, 304-314 (1997)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Fujii, Hiroshi et al.: Heme degtadation mechanism by heme oxygenase : conversion of a-meso-hydroxyheme to verdoheme IXalpha.In Oxygen Homeostasis and Its Dynamics (Ishimura, Y., Shimada, H., and Suematu, M., eds), Spring-Verlag, Tokyo, 315-321 (1997)
Description
「研究成果報告書概要(欧文)」より
