Purification of L‐Glutamate decarboxylase from rabbit brain and preparation of a monospecific antiserum

L‐Glutamate decarboxylase (GAD), the enzyme responsible for the biosynthesis of gamma‐aminobutyric acid, has been purified from rabbit brain and used for the production of a monospecific rabbit antiserum. The enzyme was purified approximately 500‐fold by a combination of ion exchange, hydrophobic, hydroxyapatite, and gel filtration column chromatography, and preparative polyacrylamide gel electrophoresis. The preparation thus obtained was injected into a rabbit, producing a polyspecific antiserum. This first antiserum was used for the preparation of an immunoprecipitate containing GAD; injections of the immunoprecipitate into a second rabbit led to the production of a second, monospecific anti‐GAD serum. The specificity of the antiserum for GAD has been demonstrated by enzyme precipitation, immunodiffusion, line immunoelectrophoresis, gel filtration chromatography of GAD/anti‐GAD immune complexes, and immunocytochemistry in the rat cerebellum.