The Molecular Architecture for the Intermediate Filaments of Hard α-Keratin Based on the Superlattice Data Obtained from a Study of Mammals Using Synchrotron Fibre Diffraction
Figure 4
These three patterns are background-corrected equatorial plots, taken over 1 mm on either side of the meridional axis. (a) shows the complete plot showing sets of “spots” and arcs. There were usually 9 spots, the one nearest the centre illustrated in (b) giving the centre to centre distance between the IFs. The other “spots” are the various orders of the Bessel functions from which the IF and tetramer (protofibril) radii can be calculated. In most cases there were six orders available to determine the IF radii and 2 for the tetramer radii. For most samples there were 8 arcs which index onto a spacing of ~45 Å and are related to the presence of soaps [16] and one sharp arc. The sharp arc, indicated in (c), verifies the close binding of the alpha-helices forming the heterodimer since the centre to centre distance of the two alpha-helices is equal to the diameter of each single helix.
