Immunochemical studies on fluctuation of phenylalanine ammonia-lyase activity in sweet potato in response to cut injury.

Antibody toward phenylalanine ammonia-lyase (PAL) [EC 4.3.1.5] was obtained by immunization of a rabbit with highly purified PAL. The antibody reacted specifically with RAL, as demonstrated by the Ouchterlony double diffusion test, immunoelectrophoresis, and SDS polyacrylamide gel electrophoresis of the immunoprecipitate. Experiments using anti-PAL showed that PAL was not present in fresh sweet potato tissue, but appeared in response to cut injury, reaching a maximum, and then decreasing, in parallel with PAL activity. The results suggest that the development of PAL activity was due to de novo synthesis of PAL and that the decrease of PAL activity after reaching a maximum was due to proteolytic degradation of PAL.