N-methyl-4-phenylpyridinium (MPP+), the neurotoxic metabolite of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, kills dopaminergic neurons after its accumulation in mitochondria where it inhibits Complex I of the respiratory chain. MPP+ inhibits respiration by binding to both a hydrophobic and a hydrophilic site on Complex I and this inhibition is increased by the lipophilic tetraphenylboron anion (TPB-) which facilitates movement of MPP+ through membranes and its penetration to the hydrophobic binding site on Complex I. To investigate the inhibition of respiration by MPP(+)-like compounds, we have measured simultaneously NADH-linked mitochondrial respiration and the uptake and accumulation of the N-benzyl-4-styrylpyridinium and N-ethyl-4-styrylpyridinium cations in mitochondria using ion-selective electrodes. The data provide direct evidence that TPB- increases the inhibition not by increasing matrix concentration but by facilitating access to the inhibitory sites on Complex I. We have also compared the rates of uptake of MPP+ analogues of varied lipophilicity by the inner membrane and the development of inhibition of NADH oxidation, using an inverted mitochondrial inner membrane preparation and appropriate ion-selective electrodes. These experiments demonstrated that the amount of MPP+ analogue bound to the inner membrane greatly exceeded the quantity required for complete inhibition of NADH oxidation. Moreover, binding to the membrane occurred much more rapidly than the development of inhibition with all MPP+ analogues tested. This suggests that the attainment of a correct orientation of these compounds within the membrane and the binding site may be a rate-limiting step in the development of inhibition.
Skip Nav Destination
Article navigation
March 1995
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
- PDF Icon PDF LinkAdvertising
Research Article|
March 01 1995
Inhibition of complex I by hydrophobic analogues of N-methyl-4-phenylpyridinium (MPP+) and the use of an ion-selective electrode to measure their accumulation by mitochondria and electron-transport particles
M P Murphy;
M P Murphy
*Department of Biochemistry, University of Otago, Box 56, Dunedin, New Zealand
Search for other works by this author on:
M J Krueger;
M J Krueger
†Department of Biochemistry-Biophysics University of California, San Francisco, CA 94143, U.S.A.
‡Molecular Biology Division, Department of Veteran Affairs Medical Center, San Francisco, CA 94121, U.S.A.
Search for other works by this author on:
S O Sablin;
S O Sablin
†Department of Biochemistry-Biophysics University of California, San Francisco, CA 94143, U.S.A.
‡Molecular Biology Division, Department of Veteran Affairs Medical Center, San Francisco, CA 94121, U.S.A.
Search for other works by this author on:
R R Ramsay;
R R Ramsay
†Department of Biochemistry-Biophysics University of California, San Francisco, CA 94143, U.S.A.
‡Molecular Biology Division, Department of Veteran Affairs Medical Center, San Francisco, CA 94121, U.S.A.
Search for other works by this author on:
T P Singer
T P Singer
†Department of Biochemistry-Biophysics University of California, San Francisco, CA 94143, U.S.A.
§Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, U.S.A.
∥Division of Toxicology, University of California, San Francisco, CA 94143, U.S.A.
‡Molecular Biology Division, Department of Veteran Affairs Medical Center, San Francisco, CA 94121, U.S.A.
Search for other works by this author on:
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1995 The Biochemical Society, London
1995
Biochem J (1995) 306 (2): 359–365.
Citation
M P Murphy, M J Krueger, S O Sablin, R R Ramsay, T P Singer; Inhibition of complex I by hydrophobic analogues of N-methyl-4-phenylpyridinium (MPP+) and the use of an ion-selective electrode to measure their accumulation by mitochondria and electron-transport particles. Biochem J 1 March 1995; 306 (2): 359–365. doi: https://doi.org/10.1042/bj3060359
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.
Could not validate captcha. Please try again.