X-ray diffraction analysis of dehydrated myelin.

Improved X-ray diffraction data from dry nerve myelin are presented. In addition to the spacing of approx. 150 A, 44 A and 34.6 A, which have been previously reported, we identify a 14 A series. The data suggests that the hydrocarbon chains in the single bilayer (approximately equal to 60 A) is ordered, whereas in the double bilayer (approximately equal to 150 A) and in the fluid phase (approximately equal to 44 A) it is disordered. It is shown that cholesterol (approximately equal to 34.6 A) exists as a bilayer, and the 14 A series is probably another cholesterol phase.