Antibody-antigen interface

It is generally accepted that the convexity/concavity of the combining site depends largely on the radius of curvature of the antigen, since the amount of antigen surface buried in complexes is always high and the surfaces are complementary[Wilson & Stanfield, 1993,Tulip et al., 1992,Lawrence & Colman, 1993]. When applied to the actual antibody-antigen interfaces (obtained using GRASP[Nicholls et al., 1991] and defined as any antibody surface less than 2.8Å from the antigen surface) our surface comparison (Figure 2.6(a)) clearly supports this; small antigens have the most concave interfaces, followed by medium and large sized antigens respectively.