help button home button Biophys. J.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS

Biophysical Journal 71: 2823-2829 (1996)
© 1996 the Biophysical Society

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Karpefors, M
Right arrow Articles by Vänngård, T
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Karpefors, M
Right arrow Articles by Vänngård, T

Electron paramagnetic resonance studies of the soluble CuA protein from the cytochrome ba3 of Thermus thermophilus.

M Karpefors, C E Slutter, J A Fee, R Aasa, B Källebring, S Larsson and T Vänngård

Department of Biochemistry and Biophysics, Göteborg University, Sweden. martin.karpefors@bcbp.gu.se

ABSTRACT

The electron paramagnetic resonance (EPR) spectrum of the binuclear CuA center in the water-soluble subunit II fragment from cytochrome ba3 of Thermus thermophilus was recorded at 3.93, 9.45, and 34.03 GHz, and the EPR parameters were determined by computer simulations. The frequency and M1 dependence of the linewidth was discussed in terms of g strain superimposed on a correlation between the A and g values. The g values were found to be gx = 1.996, gy = 2.011, gz = 2.187, and the two Cu ions contribute nearly equally to the hyperfine structure, with magnitude of Ax magnitude of approximately 15 G, magnitude of Ay magnitude = 29 G, and magnitude of Az magnitude of = 28.5 G (65Cu). Theoretical CNDO/S calculations, based on the x-ray structure of the Paracoccus denitrificans enzyme, yield a singly occupied antibonding orbital in which each Cu is pi*-bonded to one S and sigma*-bonded to the other. In contrast to the equal spin distribution suggested by the EPR simulations, the calculated contributions from the Cu ions differ by a factor of 2. However, only small changes in the ligand geometry are needed to reproduce the experimental results.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1996 by the Biophysical Society.