Molecular geometry of antigen binding by a monoclonal antibody against 5-methylcytidine.

1. The specificity of a monoclonal IgG1 raised against a 5-methylcytidine-keyhole limpet hemocyanin conjugate was investigated by inhibition experiments with soluble competing antigens. 2. A competitive enzyme immunoassay has been set up, with the antigen immobilized on polystyrene microtitration wells. 3. The analysis of the cross-reaction profile allowed the topography of the antigen-antibody interaction to be described. 4. The binding properties of the monoclonal antibody are discussed in terms of both analytical applications and working limitations in the immunochemical study of gene methylation.