Peroxidase activity of myoglobin is enhanced by chemical mutation of heme-propionates

Takashi Hayashi, Yutaka Hitomi, Tsutomu Ando, Tadashi Mizutani, Yoshio Hisaeda, Susumu Kitagawa, Hisanobu Ogoshi

    研究成果: ジャーナルへの寄稿学術誌査読

    95 被引用数 (Scopus)

    抄録

    Peroxidase activity of a myoglobin reconstituted with a chemically modified heme 1 is reported. The heme 1 bearing a total of eight carboxylates bound to the terminal of propionate side chains is incorporated into apomyoglobin from horse heart to obtain a new reconstituted myoglobin, rMb(1), with a unique binding domain structure. The UV-vis, CD, and NMR spectra of rMb(1) are comparable with those of native myoglobin, nMb. The mixing of rMb(1) with hydrogen peroxide yields a peroxidase compound II-like species, rMb(1)-II, since the spectrum of rMb(1)-II is identical with that observed for nMb. Stoichiometric oxidation of several small molecules by rMb(1)-II, demonstrates the significant reactivity. (i) The oxidation of cationic substrate such as [Ru(NH3)6]2+ by rMb(1)-II is faster than that observed for oxoferryl species of nMb, nMb-II. (ii) Anionic substrates such as ferrocyanide are unsuitable for the oxidation by rMb(1)-II. (iii) Oxidations of catechol, hydroquinone, and guaiacol are dramatically enhanced by rMb(1)-II (14-32-fold) compared to those observed for nMb-II. Thus, the chemical modification of heme-propionates can alter substrate specificity. Steady-state kinetic measurements indicate that both the reactivity and substrate affinity toward guaiacol oxidation by rMb(1) are improved, so that the specificity, k(cat)/K(m), is 13-fold higher than that in nMb. This result strongly suggests that the artificially modified heme-propionates may increase the accessibility of neutral aromatic substrates to the heme active site. The present work demonstrates that the chemical mutation of prosthetic group is a new strategy to create proteins with engineered function.

    本文言語英語
    ページ(範囲)7747-7750
    ページ数4
    ジャーナルJournal of the American Chemical Society
    121
    34
    DOI
    出版ステータス出版済み - 9月 1 1999

    !!!All Science Journal Classification (ASJC) codes

    • 触媒
    • 化学一般
    • 生化学
    • コロイド化学および表面化学

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