Crystal structure and peroxidase activity of myoglobin reconstituted with iron porphycene

Takashi Hayashi, Dai Murata, Masatomo Makino, Hiroshi Sugimoto, Takashi Matsuo, Hideaki Sato, Yoshitsugu Shiro, Yoshio Hisaeda

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75 Citations (Scopus)

Abstract

The incorporation of an artificially created metal complex into an apomyoglobin is one of the attractive methods in a series of hemoprotein modifications. Single crystals of sperm whale myoglobin reconstituted with 13,16-dicarboxyethyl-2,7-diethyl-3,6,12,17-tetramethylporphycenatoiron(III) were obtained in the imidazole buffer, and the 3D structure with a 2.25-Å resolution indicates that the iron porphycene, a structural isomer of hemin, is located in the normal position of the heme pocket. Furthermore, it was found that the reconstituted myoglobin catalyzed the H2O 2-dependent oxidations of substrates such as guaiacol, thioanisole, and styrene. At pH 7.0 and 20°C, the initial rate of the guaiacol oxidation is 11-fold faster than that observed for the native myoglobin. Moreover, the stopped-flow analysis of the reaction of the reconstituted protein with H 2O2 suggested the formation of two reaction intermediates, compounds II- and III-like species, in the absence of a substrate. It is a rare example that compound III is formed via compound II in myoglobin chemistry. The enhancement of the peroxidase activity and the formation of the stable compound III in myoglobin with iron porphycene mainly arise from the strong coordination of the Fe-His93 bond.

Original languageEnglish
Pages (from-to)10530-10536
Number of pages7
JournalInorganic chemistry
Volume45
Issue number26
DOIs
Publication statusPublished - Dec 25 2006

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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