Abstract
Asymmetric phosphatidylcholine molecules with one acyl chain twice as long as the other, below their phase transition temperature, from a mixed interdigitated phase in which the longer acyl chain spans the entire bilayer. Experimental evidence in the literature suggests that, above their phase transition temperature, these molecules may still exhibit partial interdigitation, with the longer acyl chain extending partially into the opposite leaflet, and are packed more tightly than equivalent symmetric phosphatidylcholines. Using the fluorescence recovery after photobleaching technique, we have investigated the translational diffusion in multilayers of a liquid crystalline phase, asymmetric phosphatidylcholine, 1-stearoyl-2-capryl-phosphatidylcholine (C18C10PC). We used as a fluorescent probe either a phospholipid analog of the same acyl chain composition, NBD-C18C10PE, or the symmetric equivalent of the same molecular weight, N-(7-nitrobenzoxa-2,3-diazol-4-yl)-dimyristoyl-phosphatidyle thanolamine (NBD-DMPE). Translational diffusion coefficients were also determined by using both probes in multilayers of dimyristoyl-phosphatidylcholine (DMPC) and in the eutectic mixture DMPC/C18C10PC (40/60 mol). We found that in a given host lipid, NBD-C18C10PE and NBD-DMPE diffuse at the same rate, which suggests that their bilayer free area is almost identical. This result can be explained by considering that in the liquid crystalline state, the increase in molecular packing is compensated by an increase in acyl chain dynamics. This view, which is supported by literature data, clearly suggests that the acyl chain interdigitation occurring in the liquid crystalline phase is highly dynamic.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Almeida P. F., Vaz W. L., Thompson T. E. Lateral diffusion in the liquid phases of dimyristoylphosphatidylcholine/cholesterol lipid bilayers: a free volume analysis. Biochemistry. 1992 Jul 28;31(29):6739–6747. doi: 10.1021/bi00144a013. [DOI] [PubMed] [Google Scholar]
- Florio E., Jarrell H., Fenske D. B., Barber K. R., Grant C. W. Glycosphingolipid interdigitation in phospholipid bilayers examined by deuterium NMR and EPR. Biochim Biophys Acta. 1990 Jun 27;1025(2):157–163. doi: 10.1016/0005-2736(90)90093-4. [DOI] [PubMed] [Google Scholar]
- Halladay H. N., Stark R. E., Ali S., Bittman R. Magic-angle spinning NMR studies of molecular organization in multibilayers formed by 1-octadecanoyl-2-decanoyl-sn-glycero-3-phosphocholine. Biophys J. 1990 Dec;58(6):1449–1461. doi: 10.1016/S0006-3495(90)82490-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huang C., Mason J. T., Levin I. W. Raman spectroscopic study of saturated mixed-chain phosphatidylcholine multilamellar dispersions. Biochemistry. 1983 May 24;22(11):2775–2780. doi: 10.1021/bi00280a028. [DOI] [PubMed] [Google Scholar]
- Koppel D. E. Fluorescence redistribution after photobleaching. A new multipoint analysis of membrane translational dynamics. Biophys J. 1979 Nov;28(2):281–291. doi: 10.1016/S0006-3495(79)85176-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lewis R. N., McElhaney R. N., Monck M. A., Cullis P. R. Studies of highly asymmetric mixed-chain diacyl phosphatidylcholines that form mixed-interdigitated gel phases: Fourier transform infrared and 2H NMR spectroscopic studies of hydrocarbon chain conformation and orientational order in the liquid-crystalline state. Biophys J. 1994 Jul;67(1):197–207. doi: 10.1016/S0006-3495(94)80470-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lin H., Huang C. Eutectic phase behavior of 1-stearoyl-2-caprylphosphatidylcholine and dimyristoylphosphatidylcholine mixtures. Biochim Biophys Acta. 1988 Dec 8;946(1):178–184. doi: 10.1016/0005-2736(88)90471-3. [DOI] [PubMed] [Google Scholar]
- Mason J. T. Properties of phosphatidylcholine bilayers as revealed by mixed-acyl phospholipid fluorescent probes containing n-(9-anthroyloxy) fatty acids. Biochim Biophys Acta. 1994 Aug 24;1194(1):99–108. doi: 10.1016/0005-2736(94)90207-0. [DOI] [PubMed] [Google Scholar]
- McIntosh T. J., Simon S. A., Ellington J. C., Jr, Porter N. A. New structural model for mixed-chain phosphatidylcholine bilayers. Biochemistry. 1984 Aug 28;23(18):4038–4044. doi: 10.1021/bi00313a005. [DOI] [PubMed] [Google Scholar]
- Pearson R. H., Pascher I. The molecular structure of lecithin dihydrate. Nature. 1979 Oct 11;281(5731):499–501. doi: 10.1038/281499a0. [DOI] [PubMed] [Google Scholar]
- Slater J. L., Huang C. H. Interdigitated bilayer membranes. Prog Lipid Res. 1988;27(4):325–359. doi: 10.1016/0163-7827(88)90010-0. [DOI] [PubMed] [Google Scholar]
- Tardieu A., Luzzati V., Reman F. C. Structure and polymorphism of the hydrocarbon chains of lipids: a study of lecithin-water phases. J Mol Biol. 1973 Apr 25;75(4):711–733. doi: 10.1016/0022-2836(73)90303-3. [DOI] [PubMed] [Google Scholar]
- Vaz W. L., Clegg R. M., Hallmann D. Translational diffusion of lipids in liquid crystalline phase phosphatidylcholine multibilayers. A comparison of experiment with theory. Biochemistry. 1985 Jan 29;24(3):781–786. doi: 10.1021/bi00324a037. [DOI] [PubMed] [Google Scholar]
- Vaz W. L., Hallmann D., Clegg R. M., Gambacorta A., De Rosa M. A comparison of the translational diffusion of a normal and a membrane-spanning lipid in L alpha phase 1-palmitoyl-2-oleoylphosphatidylcholine bilayers. Eur Biophys J. 1985;12(1):19–24. doi: 10.1007/BF00254091. [DOI] [PubMed] [Google Scholar]
- Zhu T., Caffrey M. Thermodynamic, thermomechanical, and structural properties of a hydrated asymmetric phosphatidylcholine. Biophys J. 1993 Aug;65(2):939–954. doi: 10.1016/S0006-3495(93)81108-1. [DOI] [PMC free article] [PubMed] [Google Scholar]