SORs (superoxide reductases) are enzymes involved in bacterial resistance to reactive oxygen species, catalysing the reduction of superoxide anions to hydrogen peroxide. So far three structural classes have been identified. Class I enzymes have two iron-centre-containing domains. Most studies have focused on the catalytic iron site (centre II), yet the role of centre I is poorly understood. The possible roles of this iron site were approached by an integrated study using both classical and fast kinetic measurements, as well as direct electrochemistry. A new heterometallic form of the protein with a zinc-substituted centre I, maintaining the iron active-site centre II, was obtained, resulting in a stable derivative useful for comparison with the native all-iron from. Second-order rate constants for the electron transfer between reduced rubredoxin and the different SOR forms were determined to be 2.8×107 M−1·s−1 and 1.3×106 M−1·s−1 for SORFe(IIII)-Fe(II) and for SORFe(IIII)-Fe(III) forms respectively, and 3.2×106 M−1·s−1 for the SORZn(II)-Fe(III) form. The results obtained seem to indicate that centre I transfers electrons from the putative physiological donor rubredoxin to the catalytic active iron site (intramolecular process). In addition, electrochemical results show that conformational changes are associated with the redox state of centre I, which may enable a faster catalytic response towards superoxide anion. The apparent rate constants calculated for the SOR-mediated electron transfer also support this observation.
Skip Nav Destination
Article navigation
September 2011
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
- PDF Icon PDF LinkEditorial Board
Research Article|
August 26 2011
New spectroscopic and electrochemical insights on a class I superoxide reductase: evidence for an intramolecular electron-transfer pathway
Filipe Folgosa;
Filipe Folgosa
1REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Search for other works by this author on:
Cristina M. Cordas;
Cristina M. Cordas
1REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Search for other works by this author on:
Joana A. Santos;
Joana A. Santos
1
1REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Search for other works by this author on:
Alice S. Pereira;
Alice S. Pereira
1REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Search for other works by this author on:
José J. G. Moura;
José J. G. Moura
1REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
Search for other works by this author on:
Pedro Tavares;
Pedro Tavares
2
1REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
2Correspondence may be addressed to either of these authors (email pedro.tavares@dq.fct.unl.pt or isa@dq.fct.unl.pt).
Search for other works by this author on:
Isabel Moura
Isabel Moura
2
1REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
2Correspondence may be addressed to either of these authors (email pedro.tavares@dq.fct.unl.pt or isa@dq.fct.unl.pt).
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
May 10 2011
Revision Received:
June 14 2011
Accepted:
June 17 2011
Accepted Manuscript online:
June 17 2011
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2011 Biochemical Society
2011
Biochem J (2011) 438 (3): 485–494.
Article history
Received:
May 10 2011
Revision Received:
June 14 2011
Accepted:
June 17 2011
Accepted Manuscript online:
June 17 2011
Citation
Filipe Folgosa, Cristina M. Cordas, Joana A. Santos, Alice S. Pereira, José J. G. Moura, Pedro Tavares, Isabel Moura; New spectroscopic and electrochemical insights on a class I superoxide reductase: evidence for an intramolecular electron-transfer pathway. Biochem J 15 September 2011; 438 (3): 485–494. doi: https://doi.org/10.1042/BJ20110836
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Captcha Validation Error. Please try again.