Abstract:
:Raman spectroscopic data indicate that the conformations of the two hydrocarbon chains of dipalmitoyl phosphatidylcholine in aqueous dispersions of the lipid differ signficantly. The compounds 1-palmitoyl, 2-palmitoyl-d31-3-sn-phosphatidylcholine and 1-palmitoyl-d31, 2-palmitoyl-3-sn-phosphatidylcholine were synthesized. Aqueous dispersions of these phospholipids display very similar phase behavior, with both premelting and melting transitions at nearly identical temperatures, midway between the comparable transition temperatures of undeuterated and completely deuterated dipalmitoyl phosphatidylcholine. We have monitored the state of chains 1 and 2 of these molecules simultaneously and independently by Raman spectroscopy. Raman difference spectra taken between samples of the two compounds under identical conditions show significant features. We attribute these spectral differences to nonequivalent conformations of the fatty acyl chains attached at positions 1 and 2 on the glycerol backbone. Below the pretransition the conformation of chain 2 is, on average, slightly less all-trans than is the chain at position 1. There is some evidence that the conformations of the terminal methyl group of the two chains are significantly different at low temperatures.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Gaber BP,Yager P,Peticolas WLdoi
10.1016/S0006-3495(78)85413-7subject
Has Abstractpub_date
1978-12-01 00:00:00pages
677-88issue
3eissn
0006-3495issn
1542-0086pii
S0006-3495(78)85413-7journal_volume
24pub_type
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