Blue myoglobin reconstituted with an iron porphycene shows extremely high oxygen affinity

Takashi Hayashi, Hirohisa Dejima, Takashi Matsuo, Hideaki Sato, Dai Murata, Yoshio Hisaeda

    Research output: Contribution to journalArticlepeer-review

    108 Citations (Scopus)

    Abstract

    Myoglobin will be a good scaffold for engineering a function into proteins. To modulate the physiological function of myoglobin, almost all approaches have been demonstrated by site-directed mutagenesis, however, there are few studies which show a significant improvement in the function. In contrast, we focused on the replacement of heme in the protein with an artificial prosthetic group. Recently, we prepared a novel myoglobin reconstituted with an iron porphycene as a structural isomer of mesoheme. The bluish colored reconstituted myoglobin is relatively stable and the deoxymyoglobin reversibly binds ligands. Interestingly, the O2 affinity of the reconstituted myoglobin, 1.1 × 109 M-1, is a significant 1,400-fold higher than that of the native myoglobin. Furthermore, the unfavorable autoxidation kinetics show 7-fold decrease in rate for the reconstituted myoglobin relative to the native myoglobin, indicating the stable oxy-form against autoxidation. The net results come from the slow dissociation of the O2 ligand in the reconstituted myoglobin, koff = 0.11 s-1, because of the formation of strong hydrogen bond between His64 and negatively charged dioxygen. The present study indicates that the replacement of native heme with an artificially created prosthetic group will give us a unique function into a hemoprotein.

    Original languageEnglish
    Pages (from-to)11226-11227
    Number of pages2
    JournalJournal of the American Chemical Society
    Volume124
    Issue number38
    DOIs
    Publication statusPublished - Sep 25 2002

    All Science Journal Classification (ASJC) codes

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

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