Deuterium nuclear magnetic resonance study of the interaction of branched chain compounds (phytanic acid, phytol) with a phospholipid model membrane
✍ Scribed by Junshi Yue; Jenifer L. Thewalt; Robert J. Cushley
- Publisher
- Elsevier Science
- Year
- 1988
- Tongue
- English
- Weight
- 631 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0009-3084
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✦ Synopsis
Deuterium nuclear magnetic resonance (2H-NMR) spectra have been determined for 50 wt% aqueous dispersions of 1 -palmitoyl(stearoyl)-2-[2H3, ]palmitoyl-sn -glycero-3-phosphocholinc (PC-d 3 I) containing 20 tool% of the isoprenoid compounds phytol or phytanic acid over the temperature range -5--55°C. Concentration effects of the isoprenoid compounds are also reported. First momenta (MI) and order parameters were calculated from the spectra. 20 Moi% of either branched chain compound causes an approximate 9% increase in the mean order parameter Soa. Significant effects are seen on the 1'C-d31 phase behavior. 20 Mol% of either branched chain compound causes the gel to liquid crystalline onset temperature (T,) to drop to 28°C from 38°C for PC-d31 alone, as seen from the temperature dependent MI values. The melting range ([Tr--T,I) is ~l.5°C for PC-d31 and ~ll°C for PC-d3t containing 20 mol% of the branched chain compounds. This is in direct contrast to their straight chain analogues, hexadecanol and palmitic acid, which have been shown to elevate the phase transition temperature. The isoprenoid compounds cause significant disruption of the gel phase, forcing nearest neighbor phospholipid chains apart. Transverse relaxation times (T2e, the time constant for decay of the quadrupolar echo) have been determined over the temperature range -5--50°(2. Possible explanation for the effect of the isoprenoid compounds on the dynamic structure of phospholipids in the bilayer are proffered.