Structure of soncanavalin A at 4 A resolution.
Concanavalin A, a phytohemagglutinin isolated from the jack bean, crystallizes at pH 6.8 in the orthorhombic space group 1222 with a = 89.9, b = 87.2, and c = 63.1 A. We have analyzed x-ray diffraction intensity data to 4 A resolution on native concanavalin A and five heavy-metal derivatives: lead, mersalyl, chloroplatinate, uranyl, and o-mercuri-p-nitrophenol. Heavy-atom positions, occupancies, and isotropic thermal parameters have been refined by least-squares methods. The electron density maps clearly show the molecular shape and the packing of the concanavalin A molecules. The asymmetric unit (mol wt 27,000) forms an elliptical dome or "gumdrop" with a base of approximately 46 x 26 A and a height of 42 A. The subunits are paired across 2-fold axes parallel to the c-axis to form dimers. The dimers are in turn paired across points of D(2) symmetry to form tetramers of roughly tetrahedral shape. Each unit has a depression located on the surface which could be the site of saccharide binding. In many regions we have been able to trace the course of the polypeptide chain.
D003208:Concanavalin A / Q000032:analysis; D003460:Crystallization; D004583:Electrons; D007854:Lead / Q000032:analysis; D037102:Lectins / Q000032:analysis*; D008628:Mercury / Q000032:analysis; D008970:Molecular Weight; D009596:Nitrophenols / Q000032:analysis; D009941:Organomercury Compounds / Q000032:analysis; D010984:Platinum / Q000032:analysis; D014501:Uranium / Q000032:analysis; D014961:X-Ray Diffraction
D037102:Lectins; D009596:Nitrophenols; D009941:Organomercury Compounds; D003208:Concanavalin A; D007854:Lead; D010984:Platinum; D014501:Uranium; D008628:Mercury