NMR Studies of Fatty Acids and Phospholipids.

Abstract

A balloon technique was used to hydrogenate 9-octadecenoic acid (oleic acid) and deuterate dipalmitoleoylphosphatidylcholine, a 16-carbon acyl chain phospholipid with unsaturation at the 9,10 position. This technique consists of a specially designed twin-flask apparatus with an attached pipet bulb to control the pressure. The hydrogen or deuterium gas was generated in the flask connected to a second flask containing the fatty acid (or phospholipid) and the catalyst (platinum tetrachloride on activated charcoal). The gases were generated from the mixture of sodium borohydride and HCl for the hydrogenation synthesis, sodium borodeuteride and DCl for the deuteration synthesis. Proton NMR showed that the hydrogenation and deuteration syntheses were successful and that the products were pure. The selectively deuterated samples will be used in deuterium NMR studies. The phase transition behavior of dipalmitoylphosphatidylcholine (DPPC) was studied using P-31 NMR spectroscopy. The phase transition of the DPPC multilayers was monitored by measuring the chemical shift anisotropy (CSA) of the P-31 nuclei. The phase transition of DPPC multilayers by measuring the chemical shift anisotropy (CSA) of the P-31 nuclei. At 313 EK, the CSA was found to be 42 ppm, where at 303 EK, the CSA was 49 ppm, showing the increase in CSA as the temperature decreased.