Crystallization of intact monoclonal antibodies
Attempts were made to crystallize four monoclonal antibodies, one IgG2ak and three IgG1k. Using a PEG 3350 screen combined with detergents, and developed from our experiments with an IgG2ak antibody specific for canine lymphoma cells,1,2 crystals have now been obtained of two of these four immunoglobulins, an antiphenytoin and an antiphenobarbital antibody. A complex between the antiphenobarbital antibody and its drug antigen crystallized as well. The antibody for phenytoin has, to this point, produced only clustered microcrystals, marginally suitable for X-ray analysis. Single crystals of the IgG1k antibody against phenobarbital, however, were characterized by X-ray diffraction to be primitive monoclinic, with unit cell dimensions a = 67 A, b = 193 A, c = 74 A, and β = 110°. These crystals have an entire IgG1k molecule as the asymmetric unit and they diffract to at least 3.2 A resolution. © 1995 Wiley-Liss, Inc.