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Coordination environment and fluoride binding of type 2 copper in the blue copper protein ascorbate oxidase

Dawson, John H. and Dooley, David M. and Gray, Harry B. (1980) Coordination environment and fluoride binding of type 2 copper in the blue copper protein ascorbate oxidase. Proceedings of the National Academy of Sciences of the United States of America, 77 (9). pp. 5028-5031. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:DAWpnas80

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Abstract

The coordination environment of the type 2 (nonblue) copper in native ascorbate oxidase (L-ascorbate:oxygen oxidoreductase, EC 1.10.3.3) and of a derivative of the enzyme having the type 1 (blue) copper reversibly bleached has been examined by electron paramagnetic resonance (EPR) spectroscopy. In the g\perp region of the spectrum of bleached ascorbate oxidase, a seven-line superhyperfine pattern is seen that is attributed to the presence of three nitrogen-donor ligands to a type 2 copper having tetragonal geometry. The superhyperfine splitting patterns in the g|| region of the EPR spectra of native and bleached ascorbate oxidase show that as many as two fluorides may bind to type 2 copper. Because fluoride inhibits the enzyme competitively with respect to ascorbic acid, it is proposed that the type 2 copper is part of the ascorbate binding site.


Item Type:Article
Additional Information:Copyright © 1980 by the National Academy of Sciences. Contributed by Harry B. Gray, May 9, 1980. We thank Professor C. R. Dawson and Dr. Ronald Strothkamp for numerous helpful discussions regarding details of the purification procedures and Dr. Maria Linder for the gel electrophoretic analysis. J.H.D. acknowledges National Institutes of Health Postdoctoral Fellowship IF32CA05748-01 (1976-1978). D. M.D. acknowledges a National Institutes of Health Predoctoral Traineeship (1974-1978). This research was supported by National Science Foundation Grant CHE77-11389. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.
Subject Keywords:nonblue copper, electron paramagnetic resonance, square planar geometry, nitrogenous ligands
Record Number:CaltechAUTHORS:DAWpnas80
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:DAWpnas80
Alternative URL:http://www.pnas.org/cgi/content/abstract/77/9/5028
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:942
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:15 Nov 2005
Last Modified:14 Nov 2014 19:18

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