Studies on reconstituted myoglobins and hemoglobins. I. role of the heme side chains in the oxygenation of myoglobin

Kuniyasu Kawabe, Kazuhiko Imaizumi, Kiyohiro Imai, Itiro Tyuma, Hisanobu Ogoshi, Takahisa Iwahara, Zen Ichi Yoshida

研究成果: Article査読

16 被引用数 (Scopus)

抄録

To clarify the functional role of the 2- and 4-side chains of heme in myoglobin oxygenation, we synthesized several new hemins carrying nonnatural side chains at positions 2 and 4, reconstituted myoglobins with them, and investigated their optical, ionization, and oxygen-binding properties. The absorption maxima for most of the reconstituted myoglobins except those reconstituted with hemins having carbonyl groups, no matter whether they are oxy-, deoxy-, or carbon monoxy-form, shifted by at most 20 nm toward shorter wavelengths than protoheme-myoglobin. The absorption spectrum is more affected by resonance effects than by inductive effects of the peripheral side chains of heme. Differences in optical and oxygenation properties between isomeric myoglobins carrying hemes with different side chains at positions 2 and 4 indicate that the 2- and 4-side chains of heme are functionally nonequivalent, as previously shown by Sono and Asakura [(1975) J. Biol. Chem. 250, 5227-5232] for monoformyl-monovinylheme myoglobins. Modification of the 4-side chain exerts greater influence on the oxygen affinity than that of the 2-side chain. The extrapolation method proposed by Sono and Asakura to correct for the protein factor seems to be applicable only as a special case and does not apply to the isomeric myoglobins studied by us. There was not correlation between pK2

本文言語English
ページ(範囲)1703-1712
ページ数10
ジャーナルJournal of Biochemistry
92
6
出版ステータスPublished - 1982 10
外部発表はい

ASJC Scopus subject areas

  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Physiology (medical)
  • Radiology Nuclear Medicine and imaging
  • Molecular Biology
  • Biochemistry

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