Alkyl peroxides reveal the ring opening mechanism of verdoheme catalyzed by heme oxygenase

Toshitaka Matsui, Kohei Omori, Hiromichi Jin, Masao Ikeda-Saito

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

Heme oxygenase (HO) catalyzes heme catabolism through three successive oxygenation steps where the substrate heme itself activates O2. Although a rate-determining step of the HO catalysis is considered as third oxygenation, the verdoheme degradation mechanism has been the least understood in the HO catalysis. In order to discriminate three possible pathways proposed for the verdoheme ring-opening, we have examined reactions of the verdoheme-HO-1 complex with alkyl peroxides, namely MeOOH. Under reducing conditions, the MeOOH reaction afforded two novel products whose absorption spectra are similar to but slightly different from that of biliverdin. HPLC, ESI-MS, and NMR analysis show that these products are 1- and 19-methoxy-deoxy-biliverdins. The addition of a methoxy group at one end of the linear tetrapyrrole unambiguously indicates transient formation of the Fe-OOMe intermediate and rearrangement of its terminal methoxy group to the α-pyrrole carbon. The corresponding OH transfer of the Fe-OOH species is highly probable in the H2O2-dependent verdoheme degradation and is likely to be the case in the O2-dependent reaction catalyzed by HO as well.

Original languageEnglish
Pages (from-to)4220-4221
Number of pages2
JournalJournal of the American Chemical Society
Volume130
Issue number13
DOIs
Publication statusPublished - 2008 Apr 2

ASJC Scopus subject areas

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

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