A P-NMR study of structural and functional aspects of phosphate and phosphonate distribution in Tetrahymena

³¹P-NMR has been used to study the chemical nature of cytoplasmic components of live Tetrahymena in a non-invasive manner. The technique has further been used to characterize the physical behaviour of lipids extracted from this organism. In particular, we have shown the presence of large quantities of pyrophosphate and of tripolyphosphate in acid extracts of the organism. These are not detectable in the live cell due to the motionally rigid nature of the storage granules. We have characterized the distribution of phosphonic acids in the organism and followed the phase behaviour of the extracted cell lipids. Aqueous dispersions of extracted lipid show both bilayer and non-bilayer behaviour in the range of the growth temperature. The phosphonolipid in Tetrahymena appears to play a role similar to that of phosphatidylethanolamine in regulating the phase behaviour of the membrane. The high degree of unsaturation in the fatty acids of Tetrahymena is most likely responsible for the polymorphic phase behaviour observed near the growth temperature.