Infrared spectra and the chain organization of erythrocyte membranes

Changes in the intensity of the 720 cm(-1) band were followed in the infrared spectra of the human erythrocyte membrane and its total lipid extract, recorded at various temperatures. These changes are interpreted in terms of the configuration of the lipid hydrocarbon chains within the membrane. Effects of temperature, sonication, removal of lipids, and organic solvents on the amide I and II bands, associated with protein conformations, were also studied.

Studies of chlorophyll-lipid-water systems

Preliminary studies of the electronic absorption spectra of chlorophyll molecules in aqueous glycolipid and phospholipid dispersions are reported. The spectra show a shift for the red peak of chlorophyll of some 10 millimicrons to longer wavelength compared with the spectrum of chlorophyll in ether. Photochemical studies were carried out with cytochrome c incorporated into the aqueous layers separating the lipid bilayers.

Physical studies of phospholipids. 3. Electron microscope studies of some pure fully saturated 2,3-diacyl-DL-phosphatidyl-ethanolamines and phosphatidyl-cholines

On heating pure, fully saturated 2,3-diacyl-DL-phosphatidyl-ethanolamines and 2,3-diacylphosphatidyl-cholines (lecithins) in water to the transition temperature at which large endothermic heat changes occur, they are observed, by light microscopy, to form myelin figures. This result is discussed in terms of the large difference in the transition temperature for "melting" of the hydrocarbon chains of unsaturated and saturated phospholipids and is illustrated by means of differential thermal analysis (D.T.A.) curves. These structures have been examined by electron microscopy after negative staining and after reaction with osmium tetroxide. Typical phospholipid lamella structures are seen in the phosphatidylcholines after negative staining, and in the phosphatidyl-ethanolamines after both negative staining and osmium fixation. The distances across these lamellae have been measured. Some preliminary investigations of the nature of the osmium tetroxide reaction with the phosphatidyl-ethanolamines have been made.