Contribution of heme-propionate side chains to structure and function of myoglobin: chemical approach by artificially created prosthetic groups

Takashi Hayashi, Takashi Matsuo, Yutaka Hitomi, Kazufumi Okawa, Akihiro Suzuki, Yoshitsugu Shiro, Tetsutaro Iizuka, Yoshio Hisaeda, Hisanobu Ogoshi

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

Horse heart myoglobin was reconstituted with mesohemin derivatives methylated at the 6- or 7-position to evaluate the role of the heme-6-propionate or heme-7-propionate side chain in the protein. The association and dissociation of the O2 binding for the deoxymyoglobin with 6-methyl-7-propionate mesoheme are clearly accelerated. Furthermore, the myoglobin with 6-methyl-7-propionate mesoheme shows fast autoxidation from oxymyoglobin to metmyoglobin compared to the myoglobin with 6-propionate-7-methyl heme and the reference protein. These results indicate the 6-propionate plays an important physiological role in the stabilization of oxymyoglobin because of the formation of a salt-bridge with the Lys45. The acceleration of CO binding rate is observed for the myoglobin with 6-propionate-7-methyl mesoheme, suggesting that the replacement of the 7-propionate with a methyl group has an influence on the His93-heme iron coordination. The structural perturbation of His93 imidazole was also supported by 1H NMR spectra of cyanide and deoxy forms of the myoglobin with 6-propionate-7-methyl mesoheme. Thus, it is found that the 7-propionate regulates the hydrogen-bonding network and His93-heme iron coordination in the proximal site.

Original languageEnglish
Pages (from-to)94-100
Number of pages7
JournalJournal of inorganic biochemistry
Volume91
Issue number1
DOIs
Publication statusPublished - Jul 25 2002

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Inorganic Chemistry

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