17 

 1988a). Although kinetic properties have been studied for PPO from 

 various sources of vegetables and fruits (Schwimmer, 1981) and more 

 recently from crustaceans (Chen et al., 1991a; Ferrer et al., 1989a; Rolle 

 et al., 1991), little comparative biochemical information exists between 

 PPO from plants and crustaceans. A preliminary study conducted in this 

 laboratory revealed that Western Australian lobsters were far less 

 susceptible than the Florida spiny lobsters to melanosis during storage at 

 refrigeration temperature. A similar phenomenon was observed on pink 

 shrimp {Penaeus duorarum) in comparison to white shrimp {Penaeus 

 setiferus) (Simpson et al . , 1988a). These workers characterized the PPO 

 properties and they attributed the difference in susceptibility to 

 melanosis to the varied physiological efficiency of the enzyme and the 

 distribution of phenolic substrates in the shrimp (Simpson et al . , 1988a). 

 Koburger et al . (1985) also showed that South African lobster tails were 

 less susceptible to melanosis than Florida spiny lobster tails. Since the 

 water habitat of Western Australian lobster is colder than that of Florida 

 spiny lobster, it is speculated that the PPO activity for these two 

 species could be different. Thus, the objectives of this study were to 

 characterize the PPO from these two lobster species and to compare their 

 kinetic properties to PPOs from other plant and crustacean sources. 



Materials and Methods 



Fresh Florida spiny lobster {Panulirus argus) tails obtained from 

 the Whitney Marine Laboratory at Marine! and, FL were transported in ice to 

 the laboratory and stored at -20°C. Frozen Western Australian lobster 

 {Panulirus cygnus) tails were purchased from the Beaver Street Foods 



