Biological Sciences: Lamellar Structure of Bleached and Unbleached Rod Photoreceptor Membranes

Small-angle X-ray data processing for planar multilayered structures. 2. Experimental determination of the parameters for retinal photoreceptors and sarcoplasmic reticulum membranes

“…The correctness of the electron-density profile obtained using data from slit-collimated X-ray patterns is, therefore, dependent on the choice of the correction factor. Many workers in this field (Blaurock & Wilkins, 1969;Corless, 1972;Dupont, Harrison & Hasselbach, 1973) have used the correction factor C(h) =h by analogy with crystal-powder diffraction. Electron-density profiles computed using either C(h) = h or C(h)= 1 are quite different (Worthington, 1973;Liu & Worthington, 1974;Rosenkrantz, 1977).…”

A rhodopsin—lipid—water lamellar system: Its characterisation by x‐ray diffraction and electron microscopy

“…The electron density profile deduced from the diffraction intensities has the general appearence of a lipid bilayer ( fig. 2) and does not differ very markedly from the electron density profile of the pure lipids, or of other membranes at the same resolution (30 A) [7,8]. It would be difficult to draw accurate conclusions from this type of profile.…”

Direct X-ray determination of the electron-density profile of the nerve myelin membrane, with paracrystalline lattice distortions taken into account

“…Such stepfunction models imply sharp discontinuities in the electrondensity levels. The work of several authors on biological membranes, for example the photosynthetic membrane (Kreutz, 1968(Kreutz, , 1970 and retinal rod membranes (Corless, 1972), shows that the conventional step function may not be suitable to depict the electron-density profiles of such biological membranes. Levine (1973) has pointed out that although the Fourier transforms of such models are easy to calculate, one requires an infinite number of structure factors in order to construct the sharp discontinuities: this is a serious disadvantage.…”