Cross-reactivity of antibodies to chicken brain choline acetyltransferase with mammalian enzyme

Abstract

An antiserum was obtained from immunized rabbit after 3 subcutaneous injections of 100 μg each of a purified chicken choline acetyltransferase (ChAT) preparation, which had a specific activity of 2.32 μmol acetylcholine formed/min/mg protein. The antiserum or immunoglobulins strongly inhibited ChAT activities from chicken and mammalian brains in immunoprecipitation experiments. Furthermore, on double immunodiffusion and immunoelectrophoretic plates single precipitin lines were obtained with either pure or crude enzyme preparations from both chicken and human brain, and with crude preparations from rat and rabbit brain. Results from double immunodiffusion also showed non-identity reactions between avian and mammalian ChAT and partial identity among enzymes from different mammalian species. This study on cross-reactivity demonstrates that chicken and mammalian ChAT are non-identical enzymes, but common antibody recognition sites exist that appear to be monospecific for ChAT.