[Preparation of an insulin conjugate with beta-galactosidase from E. coli for immunoenzyme assay].

A modified procedure has been worked out for preparing a conjugate of porcine insulin with E. coli beta-galactosidase employing a heterobifunctional reagent, N-hydroxysuccinimidyl m-maleimidobenzoate. Optimal conditions for insulin acylation and subsequent coupling with beta-galactosidase were selected that afforded the conjugate in a high yield. The ability of the modified antigen to react with antibody was evaluated in the reaction of conjugate binding with immobilized monoclonal antibody to insulin. The conjugate almost completely retained the enzymatic activity and reacted with high specificity with the antibody to insulin. The conjugate can be used in competitive ELISA of insulin.