A proteinaceous inhibitor of alpha-amylase, Tendamistat, was evaluated as an immunogen to induce antibodies that mimic the enzyme activity and to investigate a new strategy to produce catalytic antibodies. Anti-Tendamistat polyclonal antibodies (pAbs) were shown to cross-react with acarbose, a strong carbohydrate inhibitor of alpha-amylases, and the alpha-amylase carbohydrate substrates, maltotetraose and maltoheptaose. Catalytic features of pAbs were characterized after denaturing natural serum alpha-amylase by treatment at pH 10 and in the presence of EDTA. A significant residual alpha-amylase activity was detected and associated with the IgG fraction, demonstrating that some antibodies behave as a functional mimic of natural amylase. Such antibodies, which behave as an "internal image" of the alpha-amylase, were used as immunogens to elicit anti-idiotype antibodies. It was demonstrated that the anti-idiotype antiserum contains a significant amount of antibodies that bind to porcine pancreatic amylase, which shows that they contain structural information from the original hapten, Tendamistat.