PHYSICAL STUDIES OF MYELIN .2. PROTON MAGNETIC RESONANCE AND INFRARED SPECTROSCOPY

Myelin (ex beef brain) has been examined by wide-line and high-resolution proton magnetic resonance (PMR) and infrared spectroscopy. These techniques are used to provide information about (a) the overall organisation of the myelin membrane, and (b) specific interactions between the membrane components. Thus, 1. 1. The proton wide-line nuclear resonance studies of myelin in excess 2H2O show a spectrum very similar to that of the total lipid of myelin swollen in 2H2O. The lipids are known to be in a lamellar arrangement in the latter situation and hence the PMR evidence is consistent with myelin itself having a lamellar organisation. Furthermore, the infrared spectroscopic evidence shows that there is a considerable degree of planar trans configuration for the lipid chains within the membrane structure. 2. 2. Sonication of myelin in 2H2O enables chemically shifted PMR lines to be observed with a high-resolution PMR spectrometer. By comparison of this spectrum with that of cholesterol-free myelin lipid, it can be deduced that cholesterol influences the myelin lipid chain mobility and that the cholesterol molecules themselves are prevented from having complete isotropic motion. This is in contradistinction to the situation of cholesterol when myelin is dissolved in chloroform-methanol. © 1969.