The kinetics of ligand binding for diverse mammalian myoglobins and the effects of substitutions outside the heme cavity

Dixie J. Goss, Joyce B. LaGow, Lawrence J Parkhurst

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Abstract

1. 1. We report rate constants for oxygen dissociation and for oxygen, carbon monoxide, azide, and cyanide binding to whale, horse, dog, beef and human myoglobins. 2. 2. For azide binding, rate constants can vary by at least a factor of two for substitutions outside the heme cavity. Azide binding may be affected by a substitution at residue 66 in the E helix, a site suggested by Case & Karplus (1979) J. molec. Biol. 132, 343 368, to be on a reactive path to the heme. 3. 3. The oxygen and CO data show that substitutions outside the heme cavity can affect rate constants by at least a factor of 1.5. 4. 4. The oxygen equilibrium constant was correlated with the metabolic rate of the corresponding species, in accord with the Wyman (1966) J. biol. Chem. 241, 115-121, model for facilitated diffusion of oxygen.

Original languageEnglish (US)
Pages (from-to)229-233
Number of pages5
JournalComparative Biochemistry and Physiology -- Part B: Biochemistry and
Volume71
Issue number2
DOIs
Publication statusPublished - 1982

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ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Molecular Biology

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