Author(s): Montfort W, Villafranca JE, Monzingo AF, Ernst SR, Katzin B,
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Abstract The x-ray crystallographic structure of the heterodimeric plant toxin ricin has been determined at 2.8-A resolution. The A chain enzyme is a globular protein with extensive secondary structure and a reasonably prominent cleft assumed to be the active site. The B chain lectin folds into two topologically similar domains, each binding lactose in a shallow cleft. In each site a glutamine residue forms a hydrogen bond to the OH-4 of galactose, accounting for the epimerimic specificity of binding. The interface between the A and B chains shows some hydrophobic contacts in which proline and phenylalanine side chains play a prominent role.
This article was published in J Biol Chem
and referenced in Journal of Bioterrorism & Biodefense