Abstract
A number of electron and nuclear magnetic resonance studies of model membranes, and biological membranes, involve time-dependent magnetic interactions diffusion relative to one another. The two-dimensional character of this motion can have a special, large effect on magnetic resonance line shapes, and relaxation rates, because of the long-time tail of the correlation function for magnetic interactions modulated by this motion. Equations are given for the specific case in which nuclear relaxation rates are enhanced due to dipolar interactions with membrane-bound spin labels. An experimental study of spin-label-enhanced 13-C nuclear relaxation in unsonicated dispersions of phosphatidylcholine is accounted for with this theory, together with the previously reported lipid diffusion constant of D congruent to 2 times 10- minus 8 cm-2/sec. Our analysis of previously reported 1-H and 13-C nuclear relaxation rates in small phospholipid vesicles produced by sonication suggests that the rate of lateral diffusion in these small vesicles may be significantly larger than 10- minus 8 cm-2/sec.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Devaux P., McConnell H. M. Lateral diffusion in spin-labeled phosphatidylcholine multilayers. J Am Chem Soc. 1972 Jun 28;94(13):4475–4481. doi: 10.1021/ja00768a600. [DOI] [PubMed] [Google Scholar]
- Godici P. E., Landsberger F. R. The dynamic structure of lipid membranes. A 13C nuclear magnetic resonance study using spin labels. Biochemistry. 1974 Jan 15;13(2):362–368. doi: 10.1021/bi00699a022. [DOI] [PubMed] [Google Scholar]
- Kornberg R. D., McConnell H. M. Lateral diffusion of phospholipids in a vesicle membrane. Proc Natl Acad Sci U S A. 1971 Oct;68(10):2564–2568. doi: 10.1073/pnas.68.10.2564. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Levine Y. K., Birdsall N. J., Lee A. G., Metcalfe J. C. 13 C nuclear magnetic resonance relaxation measurements of synthetic lecithins and the effect of spin-labeled lipids. Biochemistry. 1972 Apr 11;11(8):1416–1421. doi: 10.1021/bi00758a014. [DOI] [PubMed] [Google Scholar]
- Levine Y. K., Lee A. G., Birdsall N. J., Metcalfe J. C., Robinson J. D. The interaction of paramagnetic ions and spin labels with lecithin bilayers. Biochim Biophys Acta. 1973 Feb 16;291(3):592–607. doi: 10.1016/0005-2736(73)90464-1. [DOI] [PubMed] [Google Scholar]
- Sackmann E., Träuble H. Studies of the crystalline-liquid crystalline phase transition of lipid model membranes. I. Use of spin labels and optical probes as indicators of the phase transition. J Am Chem Soc. 1972 Jun 28;94(13):4482–4491. doi: 10.1021/ja00768a013. [DOI] [PubMed] [Google Scholar]