Abstract
The dynamics of fluorescence quenching and the organization of a series of pyrene derivatives anchored in various depths in bilayers of phosphatidylcholine small unilamellar vesicles was studied and compared with their behavior in homogeneous solvent systems. The studies include characterization of the environmental polarity of the pyrene fluorophore based on its vibronic peaks, as well as the interaction with three collisional quenchers: the two membrane-soluble quenchers, diethylaniline and bromobenzene, and the water soluble quencher potassium iodide. The system of diethylaniline-pyrene derivatives in the membrane of phosphatidylcholine vesicles was characterized in detail. The diethylaniline partition coefficient between the lipid bilayers and the buffer is approximately 5,800. Up to a diethylaniline/phospholipid mole ratio of 1:3 the perturbation to membrane structure is minimal so that all photophysical studies were performed below this mole ratio. The quenching reaction, in all cases, was shown to take place in the lipid bilayer interior and the relative quenching efficiencies of the various probe molecules was used to provide information on the distribution of both fluorescent probes and quencher molecules in the lipid bilayer. The quenching efficiency by diethylaniline in the lipid bilayer was found to be essentially independent on the length of the methylene chain of the pyrene moiety. These findings suggest that the quenching process, being a diffusion controlled reaction, is determined by the mobility of the diethylaniline quencher (with an effective diffusion coefficient D approximately 10(-7) cm2 s-1) which appears to be homogeneously distributed throughout the lipid bilayer. The pulsed laser photolysis products of the charge-transfer quenching reaction were examined. No exciplex (excited-complex) formation was observed and the yield of the separated radical ions was shown to be tenfold smaller than in homogenous polar solutions. The decay of the radical ions is considerably faster than the corresponding process in homogenous solutions. Relatively high intersystem crossing yields are observed. The results are explained on the basis of the intrinsic properties of a lipid bilayer, primarily, its rigid spatial organization. It is suggested that such properties favor ion-pair formation over exciplex generation. They also enhance primary geminate recombination of initially formed (solvent-shared) ion pairs. Triplet states are generated via secondary geminate recombination of ion pairs in the membrane interior. The results bear on the general mechanism of electron transfer processes in biomembranes.
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Selected References
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- Barenholz Y., Gafni A., Eisenberg S. Apparent microviscosity of intact and post-lipolysis ("remnant") very low density lipoprotein particles. Chem Phys Lipids. 1978 Jun;21(3):179–185. doi: 10.1016/0009-3084(78)90065-8. [DOI] [PubMed] [Google Scholar]
- 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]
- Barenholz Y., Suurkuusk J., Mountcastle D., Thompson T. E., Biltonen R. L. A calorimetric study of the thermotropic behavior of aqueous dispersions of natural and synthetic sphingomyelins. Biochemistry. 1976 Jun 1;15(11):2441–2447. doi: 10.1021/bi00656a030. [DOI] [PubMed] [Google Scholar]
- Ben Yashar V., Menashe M., Biltonen R. L., Johnson M. L., Barenholz Y. Interaction of trans-parinaric acid with phosphatidylcholine bilayers: comparison with the effect of other fluorophores. Biochim Biophys Acta. 1987 Nov 2;904(1):117–124. doi: 10.1016/0005-2736(87)90092-7. [DOI] [PubMed] [Google Scholar]
- Galla H. J., Hartmann W. Excimer-forming lipids in membrane research. Chem Phys Lipids. 1980 Oct;27(3):199–219. doi: 10.1016/0009-3084(80)90036-5. [DOI] [PubMed] [Google Scholar]
- Galla H. J., Sackmann E. Lateral diffusion in the hydrophobic region of membranes: use of pyrene excimers as optical probes. Biochim Biophys Acta. 1974 Feb 26;339(1):103–115. doi: 10.1016/0005-2736(74)90336-8. [DOI] [PubMed] [Google Scholar]
- Hresko R. C., Sugár I. P., Barenholz Y., Thompson T. E. Lateral distribution of a pyrene-labeled phosphatidylcholine in phosphatidylcholine bilayers: fluorescence phase and modulation study. Biochemistry. 1986 Jul 1;25(13):3813–3823. doi: 10.1021/bi00361a012. [DOI] [PubMed] [Google Scholar]
- Hresko R. C., Sugár I. P., Barenholz Y., Thompson T. E. The lateral distribution of pyrene-labeled sphingomyelin and glucosylceramide in phosphatidylcholine bilayers. Biophys J. 1987 May;51(5):725–733. doi: 10.1016/S0006-3495(87)83399-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lichtenberg D., Barenholz Y. Liposomes: preparation, characterization, and preservation. Methods Biochem Anal. 1988;33:337–462. doi: 10.1002/9780470110546.ch7. [DOI] [PubMed] [Google Scholar]
- Luisetti J., Möhwald H., Galla H. J. Monitoring the location profile of fluorophores in phosphatidylcholine bilayers by the use or paramagnetic quenching. Biochim Biophys Acta. 1979 Apr 19;552(3):519–530. doi: 10.1016/0005-2736(79)90196-2. [DOI] [PubMed] [Google Scholar]
- Massey J. B., Hickson D., She H. S., Sparrow J. T., Via D. P., Gotto A. M., Jr, Pownall H. J. Measurement and prediction of the rates of spontaneous transfer of phospholipids between plasma lipoproteins. Biochim Biophys Acta. 1984 Jul 6;794(2):274–280. doi: 10.1016/0005-2760(84)90156-5. [DOI] [PubMed] [Google Scholar]
- Pownall H. J., Smith L. C. Pyrene-labeled lipids: versatile probes of membrane dynamics in vitro and in living cells. Chem Phys Lipids. 1989 Jun;50(3-4):191–211. doi: 10.1016/0009-3084(89)90050-9. [DOI] [PubMed] [Google Scholar]
- Saffman P. G., Delbrück M. Brownian motion in biological membranes. Proc Natl Acad Sci U S A. 1975 Aug;72(8):3111–3113. doi: 10.1073/pnas.72.8.3111. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shinitzky M., Barenholz Y. Fluidity parameters of lipid regions determined by fluorescence polarization. Biochim Biophys Acta. 1978 Dec 15;515(4):367–394. doi: 10.1016/0304-4157(78)90010-2. [DOI] [PubMed] [Google Scholar]
- Suurkuusk J., Lentz B. R., Barenholz Y., Biltonen R. L., Thompson T. E. A calorimetric and fluorescent probe study of the gel-liquid crystalline phase transition in small, single-lamellar dipalmitoylphosphatidylcholine vesicles. Biochemistry. 1976 Apr 6;15(7):1393–1401. doi: 10.1021/bi00652a007. [DOI] [PubMed] [Google Scholar]
- Tilcock C. P. Lipid polymorphism. Chem Phys Lipids. 1986 Jun-Jul;40(2-4):109–125. doi: 10.1016/0009-3084(86)90066-6. [DOI] [PubMed] [Google Scholar]
- Turner D. C., Brand L. Quantitative estimation of protein binding site polarity. Fluorescence of N-arylaminonaphthalenesulfonates. Biochemistry. 1968 Oct;7(10):3381–3390. doi: 10.1021/bi00850a011. [DOI] [PubMed] [Google Scholar]
- Vanderkooi J. M., Callis J. B. Pyrene. A probe of lateral diffusion in the hydrophobic region of membranes. Biochemistry. 1974 Sep 10;13(19):4000–4006. doi: 10.1021/bi00716a028. [DOI] [PubMed] [Google Scholar]
- Wiener J. R., Pal R., Barenholz Y., Wagner R. R. Effect of the vesicular stomatitis virus matrix protein on the lateral organization of lipid bilayers containing phosphatidylglycerol: use of fluorescent phospholipid analogues. Biochemistry. 1985 Dec 17;24(26):7651–7658. doi: 10.1021/bi00347a023. [DOI] [PubMed] [Google Scholar]
- Yguerabide J., Foster M. C. Fluorescence spectroscopy of biological membranes. Mol Biol Biochem Biophys. 1981;31:199–269. doi: 10.1007/978-3-642-81537-9_5. [DOI] [PubMed] [Google Scholar]