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. 1972 Mar;69(3):590–593. doi: 10.1073/pnas.69.3.590

Magnetic Resonance Studies on Membrane and Model Membrane Systems: Proton Magnetic Relaxation Rates in Sonicated Lecithin Dispersions*

Alan F Horwitz 1, William J Horsley 1, Melvin P Klein 1
PMCID: PMC426513  PMID: 4501575

Abstract

We have used Fourier transform nuclear magnetic resonance methods to measure the spin-lattice and transverse relaxation times at 220 MHz of the choline N-methyl and the fatty-acid α-carbonyl, allyl, vinyl, methylene, and methyl protons of sonicated egg-yolk lecithin. Over the temperature range investigated the T1 values were, in general, similar to, but different from, one another, suggesting that the relaxation rates of all of the fatty-acid protons are not determined solely by spin-diffusion to a heat sink. Arrhenius plots of the T1 data gave activation energies similar to those for the barriers to internal rotation in alkanes. The values of the transverse relaxation rate, T2, showed a relatively large variation among the proton resonances; about 20% of the methylene protons had a T2 of 56 msec, while the remaining protons relaxed according to a distribution of values all shorter than 20 msec. Such a distribution of relaxation times is envisioned to arise from a distribution of correlation times stemming from complex motions in which extended angular excursions of the fatty acid chain are coupled to trans→gauche conformational transitions.

Keywords: PMR, nuclear relaxation, Fourier transform NMR

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Selected References

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

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