Fig. 4.
Stereo drawings of the crambin atomic structures. Bonds along the main-chain backbone are enhanced. The conformational and compositional heterogeneity at positions 7, 22 and 25 is included. Residue numbers are given near the Cα positions of Thr 1, Gly 20 and Gly 42 in each of the views. a, View, as in Fig. 3, through the thinnest dimension. b, View along c with a* running from left to right. This is approximately along the helical stem and perpendicular to the β-sheet (towards the back at the right). c, View into a* with c running from left to right. This is approximately perpendicular to the helix axes as seen from the β-arm side. These stick figures and the surface diagrams (Figs 5 and 6) were all drawn using the program PLT1 written by G. J. Quigley.