Lipid phase transitions in fatty acid-homogeneous membranes of Acholeplasma laidlawii B

✍ Scribed by Hector L. Casal; David G. Cameron; Harold C. Jarrell; Ian C.P. Smith; Henry H. Mantsch

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 527 KB
• Volume: 30
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(82)90003-2

✦ Synopsis

The thermotropic behaviour of fatty acid-homogeneous membranes of A choleplasma laidlawii B was investigated by Fourier transform infrared spectroscopy. The organism was grown at 37°C in the presence of avidin, an inh~itor of fatty acid synthesis, in a medium supplemented with pentadecanoic acid-d~, ; the enrichment of the membranes with this fatty acid was 95%. The temperature-dependent phase behaviour of the membranes was studied via the C-D stretching vibrational modes of the membrane lipids and was compared with that of the lipid extract. The high level of fatty ~cid homogeneity results in a sharp (for natural membranes) gel to liquid crystalline phase transition. The transition, in both the membranes and extracted lipids, is centered at about 6°C above the growth temperature. During the transition two principal lipid states are evident, one being more conformationally ordered than the other. The effect of proteins on the principal lipid phase transition is minimal. However, in the intact membranes there is evident a weaker, lower temperature transition, which is not evident in the extracted lipids.