EPITOPE ANALYSIS OF HUMAN INSULIN AND INTACT PROINSULIN

Residues belonging to epitopes on human insulin that were recognized b y a panel of three monoclonal antibodies were located using mutated in sulins and insulins from a number of different animal species. Epitope s on human proinsulin recognized by two monoclonal antibodies were als o identified using partially processed proinsulin species. Epitopes we re located on the C - A and B - C junctions of proinsulin and on the N -termini of the A- and B-chains and the central region of the B-chain of human insulin. Antibodies that bound proinsulin were found to induc e conformational changes in the prohormone. The presence of a well-def ined interaction between the C-peptide portion and the N-terminus of t he A-chain of the insulin moiety of intact proinsulin has also been de monstrated. The relevance of these studies to the development of two-s ite assays for the measurement of partially processed proinsulin speci es in human sera is also discussed.