Journal of Bioenergetics and Biomembranes

, Volume 9, Issue 1, pp 17–29 | Cite as

The behavior of 9-aminoacridine as an indicator of transmembrane pH difference in liposomes of natural bacterial phospholipids

  • R. Casadio
  • B. A. Melandri
Research Articles


The behavior of 9-aminoacridine as an indicator of pH differences artificially set across a membrane has been reexamined in liposomes prepared from bacterial phospholipids extracted from chromatophores ofRhodopseudomonas capsulata grown photoheterotrophically. The dye behaves as an ideal indicator for pH differences lower than about three units; at higher pH's the expected linear dependence of Q/(100-Q) vs. pH is no longer strictly observed. Similarly a linear dependence upon the volume of the liposomes added has been verified. The amine ceases to respond to pH changes when the pH of the external medium exceeds the value of 10, corresponding to the pKa of 9-aminoacridine. The apparent volume of the inner phase of liposomes, as calculated from fluorescence quenching, but not the slope of dependence of fluorescence on pH, appears to be affected by several factors, including the ionic composition, the osmolarity of the external medium, and the microscopic structure of the liposomes. Millimolar concentrations of earth-alkaline cations diminish the apparent internal volume of liposomes, in agreement with the complexing effect of these ions on phospholipid bilayers. The osmotic response of the apparent inner volume has also been verified; this parameter decreases linearly with the reciprocal of the external osmolarity, as expected from the van't Hoff relation; an osmolarity exceeding 0.3 M is, however, necessary in order to observe this effect.


Linear Dependence Fluorescence Quenching Apparent Volume Ionic Composition External Medium 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    H. Rottenberg,J. Bioenerg. 7 (1975) 61–74.Google Scholar
  2. 2.
    S. Schuldiner, H. Rottenberg, and M. Avron,Eur. J. Biochem. 25 (1972) 64–70.Google Scholar
  3. 3.
    U. Pick, H. Rottenberg, and M. Avron, in:Proceedings of the Third International Congress on Photosynthesis Research M. Avron, ed. Vol. 2, Elsevier, Amsterdam (1974) pp. 967–974.Google Scholar
  4. 4.
    D. W. Deamer, R. C. Prince, and A. R. Crofts,Biochim. Biophys. Acta 274 (1972) 323–335.Google Scholar
  5. 5.
    R. Casadio, A. Baccarini Melandri, and B. A. Melandri,Eur. J. Biochem. 47 (1974) 121–128.Google Scholar
  6. 6.
    P. Gräber and H. T. Witt,Biochim. Biophys. Acta 423 (1976) 141–163.Google Scholar
  7. 7.
    R. Casadio, A. Baccarini Melandri, and B. A. Melandri, in:Electron Transfer Chains and Oxidative Phosphorylation E. Quagliarello, S. Papa, F. Palmieri, E. C. Slater, and N. Siliprandi, eds., North Holland American Elsevier, Amsterdam, New York (1975), pp. 407–410.Google Scholar
  8. 8.
    U. Pick, H. Rottenberg, and M. AvronFEBS Lett. 32 (1973) 91–94.Google Scholar
  9. 9.
    J. W. T. Fiolet, E. P. Bakker, and K. Van Dam,Biochim. Biophys. Acta 368 (1974) 432–445.Google Scholar
  10. 10.
    I. G. Ormerod, K. S. Ormerod, and H. Gest,Arch. Biochim. Biophys. 94 (1961) 449–463.Google Scholar
  11. 11.
    A. Baccarini Melandri and B. A. Melandri,Methods Enzymol. 23 (1971) 556–561.Google Scholar
  12. 12.
    G. Rouser and S. Fleischer,Methods Enzymol. 10 (1967) 385–406.Google Scholar
  13. 13.
    V. P. Skipski and M. Barclay,Methods Enzymol. 14 (1969) 530–598.Google Scholar
  14. 14.
    C. Huang,Biochemistry 8 (1969) 344–351.Google Scholar
  15. 15.
    B. A. Melandri, A. Baccarini Melandri, A. R. Crofts, and R. J. Cogdell,FEBS Lett. 24 (1972) 141–145.Google Scholar
  16. 16.
    S. Steiner, G. A. Sojka, S. F. Conti, H. Gest, and R. L. LesterBiochim. Biophys. Acta 203 (1970) 571–574.Google Scholar
  17. 17.
    H. Träuble and H. Eibl,Proc. Natl. Acad. Sci. USA 71 (1974) 214–219.Google Scholar
  18. 18.
    S. Massari, P. Dell'Antone, R. Colonna, and G. F. Azzone,Biochemistry 13 (1974) 1038–1043.Google Scholar
  19. 19.
    S. Massari,Biochim. Biophys. Acta 375 (1975) 22–34.Google Scholar
  20. 20.
    A. J. Verkleij, B. De Kruyff, P. H. J. Th. Ververgaert, J. F. Toccane, and L. L. M. Van Deenen,Biochim. Biophys. Acta 339 (1974) 432–437.Google Scholar
  21. 21.
    R. Rendi,Biochim. Biophys. Acta 135 (1967) 333–346.Google Scholar
  22. 22.
    H. Rottenberg, T. Grunwald, and M. Avron,Eur. J. Biochem. 25 (1972) 54–63.Google Scholar
  23. 23.
    A. R. Demel,Methods Enzymol. 32 (1974) 539–554.Google Scholar
  24. 24.
    S. Schuldiner, E. Padan, H. Rottenberg, Z. Gromet-Elhanan, and M. Avron,FEBS Lett. 49 (1974) 174–177.Google Scholar
  25. 25.
    G. Vanderkooi,Biochim. Biophys. Acta 344 (1974) 307–345.Google Scholar

Copyright information

© Plenum Publishing Corporation 1977

Authors and Affiliations

  • R. Casadio
    • 1
  • B. A. Melandri
    • 1
  1. 1.Institute of BotanyUniversity of BolognaBolognaItaly

Personalised recommendations