HOMOGENEOUS CATALYTIC DEUTERATION OF FATTY ACYL CHAINS AS A TOOL TO DETECT LIPID PHASE-TRANSITIONS IN SPECIFIC MEMBRANE DOMAINS - A FOURIER-TRANSFORM INFRARED SPECTROSCOPIC STUDY

Synthetic phospholipid molecules have been deuterated by using a water soluble catalyst and deuterium gas. The physical state of both deuterated segments and unaffected bulk part of the lipid molecules can be monitored simultaneously by Fourier Transform Infrared Spectroscopy. It is shown on multilamellar phospholipid systems that the deuterated segments can be used as structural probes. Whereas the ν(C-H) frequencies represent an average conformational order along all the alkyl chains present, by following changes in ν(C-D) vibrations, mobility of those membrane domains deuterium labeled at specific depths in the hydrocarbon core can be estimated. The potential importance of this new approach in the study of biological membranes is discussed. © 1993 Academic Press.