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Intramolecular electron transfer in ascorbate oxidase is enhanced in the presence of oxygen.

Authors :
Farver O
Wherland S
Pecht I
Source :
The Journal of biological chemistry [J Biol Chem] 1994 Sep 16; Vol. 269 (37), pp. 22933-6.
Publication Year :
1994

Abstract

Intramolecular electron transfer from the type 1 copper center to the type 3 copper(II) pair is induced in the multi-copper enzyme, ascorbate oxidase, following pulse radiolytic reduction of the type 1 Cu(II) ion. In the presence of a slight excess of dioxygen over ascorbate oxidase, interaction between the trinuclear copper center and O2 is observed even with singly reduced ascorbate oxidase molecules. Under these conditions, the rate constant for intramolecular electron transfer from type 1 Cu(I) to type 3 Cu(II) increases 5-fold to 1100 +/- 300 s-1 (20 degrees C, pH 5.8) as compared to that of the same process under anaerobic conditions. This observation constitutes evidence for control of the internal electron transfer process by one of its substrates. The structural and functional significance of these findings are discussed.

Details

Language :
English
ISSN :
0021-9258
Volume :
269
Issue :
37
Database :
MEDLINE
Journal :
The Journal of biological chemistry
Publication Type :
Academic Journal
Accession number :
8083190