| Autor: |
Lin R; Department of Chemistry, University of California, Irvine 92697-2025, USA., Immoos CE, Farmer PJ |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry [J Biol Inorg Chem] 2000 Dec; Vol. 5 (6), pp. 738-47. |
| DOI: |
10.1007/s007750000163 |
| Abstrakt: |
The surfactant film methodology is used to examine the electrochemistry of manganese-substituted myoglobin. Cyclic voltammograms at different scan rates depict a dynamic exchange between two redox couples, E1 (-0.25 V vs. SCE) and E2 (-0.41 V). Similar behavior is seen for Mn-substituted cytochrome c peroxidase, but the free cofactor, Mn(protoporphyrin IX) yields a single couple (-0.32 V) under the same conditions. A square scheme is proposed which describes equilibration between two different redox pathways associated with different forms of the protein. Overlapping oxidative currents from these two couples can be deconvoluted, and a pseudo first-order rate constant of 2.3 s(-1) is obtained for the reaction following reduction of Mn(III)Mb. Experiments have been performed to probe possible mechanisms for this equilibrium, such as ligand dissociation or reversible adsorption at the electrode surface. A cofactor-induced reorganization of the protein structure is suggested as the basis of the behavior. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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