Temperature-dependent lateral diffusion of phospholipids in hepatic microsomes as studied by 31P-NMR.
The 81 MHz 31P-NMR spectra of isolated rabbit liver microsomes before and after trypsin treatment and of the total microsomal lipid extract were recorded in the 4-40 degrees C temperature range. In both treated and untreated microsomes at 4 degrees C most of the phospholipids gave rise to typical bilayer spectra whereas the lineshape of the latter in the 25-37 degrees C temperature range becomes narrower and more symmetrical. Quasi-elastic light scattering (QELS) measurements revealed that the microsomes maintain their size in the temperature region of the measurements. We interpret the lineshape changes for untreated microsomes above 25 degrees C as being determined by lateral diffusion. This is supported by lineshape calculations as a function of the lateral diffusion coefficient. The different spectral behavior of enzymatically active (untreated) and inactive (treated) microsomes suggests that the membrane proteins influence the lateral diffusion of the phospholipids.
D000818:Animals; D004058:Diffusion; D009682:Magnetic Resonance Spectroscopy; D008862:Microsomes, Liver / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D011817:Rabbits; D013696:Temperature
D010743:Phospholipids