2-DIMENSIONAL CRYSTALLIZATION OF RABBIT C-REACTIVE PROTEIN ON LIPID MONOLAYERS

Two-dimensional (2D) crystals of rabbit C-reactive protein (CRP) have been obtained by protein binding on lipid monolayers at the air/water interface, Two different types of crystalline arrays of CRP were obtai ned, by specific binding and non-specific adsorption to the lipids, El ectron crystallographic analysis of the negatively stained specimens s howed that the unit cell parameters of the CRP 2D crystals formed by s pecific binding were a = 81 Angstrom b = 78 Angstrom, gamma = 118.35 d egrees, and those formed by non-specific adsorption were a = 74 Angstr om, b = 67 Angstrom, gamma = 95.5 degrees, both with the layer group p 1, Projection maps were obtained at a resolution of 26 Angstrom and 22 Angstrom respectively, They showed that only the monomers of the CRP mere packed in the 2D arrays and the orientations of the monomers on t he lipid monolayers were different in the two types of crystals, By co mparing the two projection maps, a preliminary shape of the CRP monome r has been derived, A model of the pentameric structure of the oligome ric CRP has been proposed.