COMPARISON OF PHENOLOXIDASE ACTIVITY FROM FLORIDA SPINY LOBSTER AND WESTERN AUSTRALIAN LOBSTER

Polyphenoloxidase (PPO) isolated from cuticle of Western Australian lobster (Panulirus cygnus) and Florida spiny lobster (Panulirus argus) catalyzed oxidation of catechol and DL-beta-3,4-dihydroxyphenylalanine (DL-DOPA). The PPO from Florida lobster showed a higher substrate affinity than that from Australian lobster. They both showed higher affinity for catechol than for DL-DOPA, and optimal pH stability at 7.0. The enzymes differed with respect to activation energy and thermal stability. Electrophoretic patterns using SDS-PAGE indicated PPO from Western Australian lobster had two isoforms while Florida spiny PPO had three isoforms. These results suggest variations in enzyme activity may contribute to differences in susceptibility to melanosis between the two species.