Effect of succinylation of antibodies on their conformation and interaction with the antigen

Using succinic anhydride, a succinylated derivative of anti-urease IgG having 49 +/- 6% modification was prepared and its physicochemical and immunological properties were studied. IgG undergoes substantial changes in its native conformation on succinylation, which was mainly attributed to electrostatic destabilization of the native protein conformation. The modified IgG exhibited a decrease in its cross-reactivity with urease. This decrease is attributed to the conformational change in IgG upon succinylation and/or is due to the disruption of the lysine residues in the antigen-binding site of IgG upon succinylation, which may be involved in binding the antigen. IgG was able to bind to the specific antigen although its conformation was partially modified. Therefore, partial modification of the conformation of the antigen-binding site of IgG is permissible in order to bind to the antigen.