CaltechAUTHORS
  A Caltech Library Service

8-Azido-ATP Modification of Cytochrome c: Retardation of Its Electron-Transfer Activity to Cytochrome c Oxidase

Lin, Jian and Wu, Shuguang and Lau, Wa-to and Chan, Sunney I. (1995) 8-Azido-ATP Modification of Cytochrome c: Retardation of Its Electron-Transfer Activity to Cytochrome c Oxidase. Biochemistry, 34 (8). pp. 2678-2685. ISSN 0006-2960. doi:10.1021/bi00008a035. https://resolver.caltech.edu/CaltechAUTHORS:20180205-083519723

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20180205-083519723

Abstract

Horse heart cytochrome c has been modified by 8-azido-ATP and the electron-transfer activity of the modified cytochrome c’s to bovine heart cytochrome c oxidase (CcO) under physiological ionic strengths has been studied by the laser flash photolysis technique with 5-deazariboflavin and EDTA as the electron donor. The intermolecular electron transfer between the redox protein partners was shown to be extremely slow. The 8-azido-ATP-modified system exhibited less than 5% of the intracomplex electron-transfer rate observed between native cytochrome c and CcO under otherwise identical conditions. The binding affinity of the modified cytochrome c was greatly reduced (3 orders of magnitude) at low ionic strengths; however, it was only slightly reduced (by a factor of 2) relative to the native protein at physiological ionic strengths. Thus, the binding affinity of the ATP-cytochrome c adducts is relatively insensitive to the ionic strength compared to the native enzyme, suggesting that a different docking conformation is assumed by the ATP-cytochrome c adducts in their interaction with the oxidase. Since the redox potential of the modified cytochrome c is close to the value of its native form, we conclude that there has been a change in the docking of the cytochrome c to CcO and the electronic coupling between heme c and CUA upon 8-azido-ATP modification.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/bi00008a035DOIArticle
https://pubs.acs.org/doi/10.1021/bi00008a035PublisherArticle
ORCID:
AuthorORCID
Chan, Sunney I.0000-0002-5348-2723
Additional Information:© 1995 American Chemical Society. Published in print 28 February 1995. This work was supported by NIH Grant GM 22432 from the National Institute of General Medical Sciences, US. Public Health Service. Contribution no. 8955. We are grateful to Professor Gordon Tollin of the Department of Biochemistry, University of Arizona, Tucson, for a gift of 5-DRF. We also thank Dr. Jay Winkler, manager of the laser facility at the Beckman Institute of the California Institute of Technology, for advice and technical assistance in the laser experiments. Professor Carmichael Wallace kindly provided us with a copy of a manuscript summarizing the results of related studies prior to publication. Dr. Wallace also provided a number of helpful comments on the present study.
Funders:
Funding AgencyGrant Number
NIHGM 22432
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Chemistry and Chemical Engineering8955
Issue or Number:8
DOI:10.1021/bi00008a035
Record Number:CaltechAUTHORS:20180205-083519723
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180205-083519723
Official Citation:8-Azido-ATP Modification of Cytochrome c: Retardation of Its Electron-Transfer Activity to Cytochrome c Oxidase Jian Lin, Shuguang Wu, Wa-to Lau, and Sunney I. Chan Biochemistry 1995 34 (8), 2678-2685 DOI: 10.1021/bi00008a035
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84665
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:05 Feb 2018 23:40
Last Modified:15 Nov 2021 20:21

Repository Staff Only: item control page