1. Intramolecular Electron-Transfer Pathway for Deoxy and Zinc Myoglobins Modified withN,N,N′,N″,N″-Diethylenetriaminepentaacetatocobaltate(III)
- Author
-
Junzo Hirose, Keiichi Tsukahara, Mari Nishimine, Yuka Shioyama, and Hiroshi Takashima
- Subjects
Tris ,Chemistry ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Medicinal chemistry ,Ruthenium ,chemistry.chemical_compound ,Electron transfer ,Reaction rate constant ,Metmyoglobin ,Ionic strength ,Intramolecular force ,Hydroxymethyl - Abstract
Horse heart metmyoglobin (metMb), whose N-terminal Gly1 is linked by an N,N,N′,N″,N″-diethylenetriaminepentaacetatocobaltate(III) ion ([CoIII(dtpa)]) with an amide bond, was prepared and characterized. A one-electron reduced protein, [deoxyMb{CoIII(dtpa)}], was prepared by reduction with a methylviologen-radical cation, which was produced in situ by a photoreduction using a tris(2,2′-bipyridine)ruthenium(II) ion in the presence of disodium dihydrogen ethylenediaminetetraacetate at 25 °C, pH 7.5 (a 0.010 mol dm−3 tris(hydroxymethyl)aminomethane–HCl buffer), and an ionic strength of 0.50 mol dm−3 (NaCl). The reaction of [deoxyMb{CoIII(dtpa)}] to form [metMb{CoII(dtpa)}] obeyed a first-order rate law on the protein concentration. The first-order rate constant was dependent on the concentration of the protein, indicating that both intra- and intermolecular electron-transfer (ET) processes simultaneously occur. The latter is the reaction with excess [metMb{CoIII(dtpa)}] remaining. Both intra- and intermolecula...
- Published
- 2003
- Full Text
- View/download PDF