The three-dimensional structure of ricin at 2.8 A

W Montfort, J E Villafranca, A F Monzingo, S R Ernst, B Katzin, E Rutenber, N H Xuong, R Hamlin, J D Robertus
1987 Journal of Biological Chemistry  
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.
more » ... e interface between the A and B chains shows some hydrophobic contacts in which proline and phenylalanine side chains play a prominent role.
pmid:3558397 fatcat:4xmwhdq47bbcbjixww2wt7lbs4