Canavalin crystals

FIGURE 6.12 In (a) is the hkO diffraction plane of a P63 canavalin crystal having sixfold symmetry, and in (b) the view along the unique axis of a rhombohedral canavalin crystal that exhibits 6mm symmetry. In neither case would one choose orthogonal axes on which to index the reflections. In (a), the natural choice would be the a and b axes indicated. In (b), two choices of hexagonal axes are reasonable, but those indicated are chosen as a and b because they correspond with the real unit cell of smallest volume. 

According to the PDB X-ray crystal structure 2cna, jack bean con-canavalin A contains 43.5% /1-strand, 1.7% a-helix, and 1.3% 3io-helix,... 

Detailed reviews on the characterization of surfaces of single crystals of small and large biomolecules such as catalase, insulin, canavalin, etc. can be found in McPherson, 1999 and Ward, 2001. 

FIGURE 1.10 Crystals of a variety of proteins. In (a) hexagonal prisms of beef liver catalase. In (b) crystals of oo acid glycoprotein, in (c) Fab fragments of a murine immunoglobulin, and in (d) rhombohedral crystals of the seed storage protein canavalin. 

FIGURE 6.10 In (a) are the hOl diffraction intensities from a crystal of fructose 1,6 bisphosphatase from rabbit liver having space group 1222. In (b) is the hkO plane of reflections from C2221 canavalin. In both images the checkerboard patterns produced by systematic absences resulting from the I and C centering operations are evident. 

FIGURE 6.21 In (a), the MO diffraction plane of R3 canavalin exhibits 6mm symmetry, but because of Friedel s law it could arise as a consequence of either a true sixfold axis or a threefold axis plus the Friedel center of symmetry. In (b), the M2 image, which is along the same direction but does not contain Friedel related reflections, exhibits only threefold symmetry. This demonstrates that the crystal does in fact belong to the trigonal system and not the hexagonal system. 

FIGURE 9.11 The w = j plane of the difference Patterson map for the K2HgI4 heavy atom derivative of the hexagonal crystal form of the protein canavalin. The space group is P6, so w = is a Harker section. The derivative crystal contained two major K2HgI4 substitution sites and one minor substitution site per asymmetric unit. The Patterson peaks corresponding to those sites are marked with crosses. Note that the Patterson peak corresponding to the minor site cannot be discriminated from noise peaks in the Patterson map as is often the case. 

Figure 7.10 2-curves determined under various beam line conditions and from protein crystal Laue film data (a) SRS station 9.6 prior to mirror installation (Helliwell 1984 Helliwell et al 1989b) pea lectin. (b) SRS station 9.6 after mirror installation mercury a-amylase crystal derivative, (c) SRS station 9.7, no mirror, with 50,am aluminium filter cubic con-canavalin-A. Each curve on an arbitrary relative level. From Helliwell et al (1989a). Reproduced with the permission of the American Institute of Physics. 

Ko, T. R, Kuznetsov, Y. G., MaUdn, A. J., Day, J., and McPherson, A. 2001. X-ray diffraction and atomic force microscopy analysis of twinned crystals Rhombohedral canavalin, Acta Crystallogr D Biol Crystallogr 57, 829-839. 

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