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Accession number;00A0163482
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| Title;Mechanism of Regioselective Heme Degradation Reaction by Heme Oxygenase. |
| Author;
FUJII HIROSHI
(Inst. for Molecular Science)
ZHOU H
(Yamagata Univ., Sch. of Med.)
MIGITA TAIKO
(The Sch. of Allied Health Sei., Yamaguchi Univ.)
YOSHIDA TADASHI
(Yamagata Univ., Sch. of Med.)
IKEDA-SAITO M
(Tohoku Univ.)
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Journal Title;Abstracts. Symposium on Biofunctional Chemistry
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Journal Code:L0836A
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ISSN:
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VOL.14th;NO.;PAGE.46-47(1999)
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| Figure&Table&Reference; |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;Heme oxygenase(HO) is a microsomal enzyme which catalyzes the degradation of iron protoporphyrin IX (heme) to biliverdinIXa through the two novel heme derivatives, .ALPHA.-meso-hydroxyheme and verdohemeIX.ALPHA.. The present study shows the first evidence that the .ALPHA.-regioselectivity of HO is modulated by a carboxy group side chain located near the heme group. We have found that the replacement of the highly conserved arginine 183(R183) of HO-1 with glutamic acid (E) or aspartic acid (D) forms biliverdinIX.DELTA. isomer along with normal biliverdinIX.ALPHA.. The absorption and EPR spectra and HO catalytic activity of R183E mutant are similar to those of the wild type heme-HO complex, indicating no significant change in the active site structure of R183E mutant. The HO reactions of R183Q and R183N mutants do not produce biliverdin isomers other than the normal biliverdinIX.ALPHA.. The .ALPHA.-regioselectivity is also retained in HO mutants with R183 substituted with alanine (A) or tyrosine (Y). These results indicate that the carboxy group introduced at position 183 is directly involved in the formation of .DELTA.-biliverdin isomer. (author abst.) |
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