Skip to main content
NCBI home page
Biophysical Journal logoLink to Biophysical Journal
. 1983 Mar;41(3):381–398. doi: 10.1016/S0006-3495(83)84449-X

The molecular mechanism of action of the proton ionophore FCCP (carbonylcyanide p-trifluoromethoxyphenylhydrazone).

R Benz, S McLaughlin
PMCID: PMC1329191  PMID: 6838976

Abstract

We propose a simple model that accounts for the ability of the weak acid FCCP (Carbonylcyanide-p-trifluoromethoxyphenylhydrazone) to both transport protons across phospholipid bilayer membranes and uncouple oxidation from phosphorylation in mitochondria. Four parameters are required to characterize this model: the rate constant for the movement of A- across the membrane, kA, the rate constant for the movement of HA across the membrane, kHA, the adsorption coefficient of A- onto the membrane-solution interface, beta A, and the surface pK. These four parameters were determined from kinetic measurements on planar bilayer membranes using the charge-pulse and voltage-clamp techniques. We confirmed the adequacy of the model by determining each of these parameters independently, utilizing equilibrium dialysis, zeta potential, membrane potential, spectrophotometric, and conductance measurements. For a phosphatidylethanolamine bilayer the values of the parameters are kHA = 10(4)S-1, beta A = 3 10(-3) cm, and 6.0 less than pK less than 6.4. As predicted theoretically, the value of KA depends on both the applied voltage, V, and dielectric constant of the membrane, epsilon r; when V approaches zero and the membrane contains chlorodecane (epsilon r congruent to 2.7) kA = 700 s-1. If oxidation is coupled to phosphorylation by means of a delta microH+, and V er congruent to 2.7 for the inner membrane of the mitochondrion, the model predicts that FCCP should exert maximal uncoupling activity at a pH congruent to pK. This prediction agrees with the published experimental results.

Full text

PDF
381

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Andersen O. S., Feldberg S., Nakadomari H., Levy S., McLaughlin S. Electrostatic interactions among hydrophobic ions in lipid bilayer membranes. Biophys J. 1978 Jan;21(1):35–70. doi: 10.1016/S0006-3495(78)85507-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Andersen O. S., Fuchs M. Potential energy barriers to ion transport within lipid bilayers. Studies with tetraphenylborate. Biophys J. 1975 Aug;15(8):795–830. doi: 10.1016/S0006-3495(75)85856-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bakker E. P., Arents J. C., Hoebe J. P., Terada H. Surface potential and the interaction of weakly acidic uncouplers of oxidative phosphorylation with liposomes and mitochondria. Biochim Biophys Acta. 1975 Jun 17;387(3):491–506. doi: 10.1016/0005-2728(75)90088-2. [DOI] [PubMed] [Google Scholar]
  4. Barenholz Y., Gibbes D., Litman B. J., Goll J., Thompson T. E., Carlson R. D. A simple method for the preparation of homogeneous phospholipid vesicles. Biochemistry. 1977 Jun 14;16(12):2806–2810. doi: 10.1021/bi00631a035. [DOI] [PubMed] [Google Scholar]
  5. Benz R., Läuger P., Janko K. Transport kinetics of hydrophobic ions in lipid bilayer membranes. Charge-pulse relaxation studies. Biochim Biophys Acta. 1976 Dec 14;455(3):701–720. doi: 10.1016/0005-2736(76)90042-0. [DOI] [PubMed] [Google Scholar]
  6. Benz R., Läuger P. Kinetic analysis of carrier-mediated ion transport by the charge-pulse technique. J Membr Biol. 1976 Jun 9;27(1-2):171–191. doi: 10.1007/BF01869135. [DOI] [PubMed] [Google Scholar]
  7. Brock W., Stark G., Jordan P. C. A laser-temperature-jump method for the study of the rate of transfer of hydrophobic ions and carriers across the interface of thin lipid membranes. Biophys Chem. 1981 Aug;13(4):329–348. doi: 10.1016/0301-4622(81)85007-7. [DOI] [PubMed] [Google Scholar]
  8. Cohen F. S., Eisenberg M., McLaughlin S. The kinetic mechanism of action of an uncoupler of oxidative phosphorylation. J Membr Biol. 1977 Dec 15;37(3-4):361–396. doi: 10.1007/BF01940940. [DOI] [PubMed] [Google Scholar]
  9. Dilger J. P., McLaughlin S. G., McIntosh T. J., Simon S. A. The dielectric constant of phospholipid bilayers and the permeability of membranes to ions. Science. 1979 Dec 7;206(4423):1196–1198. doi: 10.1126/science.228394. [DOI] [PubMed] [Google Scholar]
  10. Eisenberg M., Gresalfi T., Riccio T., McLaughlin S. Adsorption of monovalent cations to bilayer membranes containing negative phospholipids. Biochemistry. 1979 Nov 13;18(23):5213–5223. doi: 10.1021/bi00590a028. [DOI] [PubMed] [Google Scholar]
  11. Gutknecht J., Tosteson D. C. Diffusion of weak acids across lipid bilayer membranes: effects of chemical reactions in the unstirred layers. Science. 1973 Dec 21;182(4118):1258–1261. doi: 10.1126/science.182.4118.1258. [DOI] [PubMed] [Google Scholar]
  12. Haydon D. A., Hladky S. B. Ion transport across thin lipid membranes: a critical discussion of mechanisms in selected systems. Q Rev Biophys. 1972 May;5(2):187–282. doi: 10.1017/s0033583500000883. [DOI] [PubMed] [Google Scholar]
  13. Hinkle P. C., McCarty R. E. How cells make ATP. Sci Am. 1978 Mar;238(3):104-17, 121-3. doi: 10.1038/scientificamerican0378-104. [DOI] [PubMed] [Google Scholar]
  14. Hladky S. B. The energy barriers to ion transport by nonactin across thin lipid membranes. Biochim Biophys Acta. 1974 May 30;352(1):71–85. doi: 10.1016/0005-2736(74)90180-1. [DOI] [PubMed] [Google Scholar]
  15. Jonsson B. H., Steiner H., Lindskog S. Participation of buffer in the catalytic mechanism of carbonic anhydrase. FEBS Lett. 1976 May 1;64(2):310–314. doi: 10.1016/0014-5793(76)80317-1. [DOI] [PubMed] [Google Scholar]
  16. Jordan P. C., Stark G. Kinetics of transport of hydrophobic ions through lipid membranes including diffusion polarization in the aqueous phase. Biophys Chem. 1979 Nov;10(3-4):273–287. doi: 10.1016/0301-4622(79)85016-4. [DOI] [PubMed] [Google Scholar]
  17. Lee A. G. Effects of charged drugs on the phase transition temperatures of phospholipid bilayers. Biochim Biophys Acta. 1978 Dec 4;514(1):95–104. doi: 10.1016/0005-2736(78)90079-2. [DOI] [PubMed] [Google Scholar]
  18. Lowry R. R., Tinsley I. J. A simple, sensitive method for lipid phosphorus. Lipids. 1974 Jul;9(7):491–492. doi: 10.1007/BF02534277. [DOI] [PubMed] [Google Scholar]
  19. Läuger P., Benz R., Stark G., Bamberg E., Jordan P. C., Fahr A., Brock W. Relaxation studies of ion transport systems in lipid bilayer membranes. Q Rev Biophys. 1981 Nov;14(4):513–598. doi: 10.1017/s003358350000247x. [DOI] [PubMed] [Google Scholar]
  20. Läuger P. Carrier-mediated ion transport. Science. 1972 Oct 6;178(4056):24–30. doi: 10.1126/science.178.4056.24. [DOI] [PubMed] [Google Scholar]
  21. MITCHELL P. Coupling of phosphorylation to electron and hydrogen transfer by a chemi-osmotic type of mechanism. Nature. 1961 Jul 8;191:144–148. doi: 10.1038/191144a0. [DOI] [PubMed] [Google Scholar]
  22. McLaughlin S. G., Dilger J. P. Transport of protons across membranes by weak acids. Physiol Rev. 1980 Jul;60(3):825–863. doi: 10.1152/physrev.1980.60.3.825. [DOI] [PubMed] [Google Scholar]
  23. McLaughlin S., Eisenberg M. Antibiotics and membrane biology. Annu Rev Biophys Bioeng. 1975;4(00):335–366. doi: 10.1146/annurev.bb.04.060175.002003. [DOI] [PubMed] [Google Scholar]
  24. Neumcke B., Läuger P. Nonlinear electrical effects in lipid bilayer membranes. II. Integration of the generalized Nernst-Planck equations. Biophys J. 1969 Sep;9(9):1160–1170. doi: 10.1016/S0006-3495(69)86443-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Neumcke B. The action of uncouplers on lipid bilayer membranes. Membranes. 1975;3:215–253. [PubMed] [Google Scholar]
  26. Roos A. Intracellular pH and intracellular buffering power of the cat brain. Am J Physiol. 1965 Dec;209(6):1233–1246. doi: 10.1152/ajplegacy.1965.209.6.1233. [DOI] [PubMed] [Google Scholar]
  27. Stark G., Ketterer B., Benz R., Läuger P. The rate constants of valinomycin-mediated ion transport through thin lipid membranes. Biophys J. 1971 Dec;11(12):981–994. doi: 10.1016/S0006-3495(71)86272-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Tsien R. Y., Hladky S. B. Ion repulsion within membranes. Biophys J. 1982 Jul;39(1):49–56. doi: 10.1016/S0006-3495(82)84489-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Verkman A. S., Solomon A. K. Kinetics of phloretin binding to phosphatidylcholine vesicle membranes. J Gen Physiol. 1980 Jun;75(6):673–692. doi: 10.1085/jgp.75.6.673. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Wilson D. F., Forman N. G. Mitochondrial transmembrane pH and electrical gradients: evaluation of their energy relationships with respiratory rate and adenosine 5'-triphosphate synthesis. Biochemistry. 1982 Mar 16;21(6):1438–1444. doi: 10.1021/bi00535a051. [DOI] [PubMed] [Google Scholar]
  31. Wilson D. F., Ting H. P., Koppelman M. S. Mechanism of action of uncouplers of oxidative phosphorylation. Biochemistry. 1971 Jul 20;10(15):2897–2902. doi: 10.1021/bi00791a016. [DOI] [PubMed] [Google Scholar]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society

RESOURCES