Lipid mobility in Acholeplasma membranes using deuteron magnetic resonance

Acholeplasma laidlawii B have been grown on media supplemented with perdeuterated lauric and palmitic acids. The lauric acid was shown to be elongated to myristic acid-d₂₃ and palmitic acid-d₂₃, and these acids were incorporated into the membrane lipids. Infrared measurements indicated the membrane proteins were predominantly α-helical. Deuteron magnetic resonance spectroscopy of the deuterated lipids in intact membranes indicated that the lipids were in a state of mobility rather similar to that of the gel state of dimyristoyl lecithin. This is consistent with our interpretation of results obtained by differential scanning calorimetry and X-ray diffraction. The existence of rigid lipid regions in organisms lacking cholesterol may not be uncommon, and may occur in E. coli also.