Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
Collection
For ¥0.57 per day, unlimited downloads CREATE MEMBERSHIP Download

toTop

If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

home > search >

Tightly-bound ubiquinone in the Escherichia coli respiratory Complex I

Author:
Verkhovsky, Michael   Bloch, Dmitry A.   Verkhovskaya, Marina  


Journal:
Biochimica et Biophysica Acta (BBA) - Bioenergetics


Issue Date:
2012


Abstract(summary):

NADH:ubiquinone oxidoreductase (Complex I), the electron input enzyme in the respiratory chain of mitochondria and many bacteria, couples electron transport to proton translocation across the membrane. Complex I is a primary proton pump; although its proton translocation mechanism is yet to be known, it is considered radically different from any other mechanism known for redox-driven proton pumps: no redox centers have been found in its membrane domain where the proton translocation takes place. Here we studied the properties and the catalytic role of the enzyme-bound ubiquinone in the solubilized, purified Complex I from Escherichia coli. The ubiquinone content in the enzyme preparations was 1.3 +/- 0.1 per bound FMN residue. Rapid mixing of Complex I with NADH, traced optically, demonstrated that both reduction and re-oxidation kinetics of ubiquinone coincide with the respective kinetics of the majority of Fe-S clusters, indicating kinetic competence of the detected ubiquinone. Optical spectroelectrochemical redox titration of Complex I followed at 270-280 nm, where the redox changes of ubiquinone contribute, did not reveal any transition within the redox potential range typical for the membrane pool, or loosely bound ubiquinone (ca. +50-+ 100 mV vs. NHE, pH 6.8). The transition is likely to take place at much lower potentials (E-m <= -200 mV). Such perturbed redox properties of ubiquinone indicate that it is tightly bound to the enzyme's hydrophobic core. The possibility of two ubiquinone-binding sites in Complex I is discussed. (C) 2012 Elsevier B.V. All rights reserved.


Page:
1550-1556


VIEW PDF

The preview is over

If you wish to continue, please create your membership or download this.

Create Membership

Similar Literature

Submit Feedback

This function is a member function, members do not limit the number of downloads