18 

 (Jacksonville, FL); these lobsters were found to contain less than 5 ppm 

 sulfite background residue when randomly selected samples from each batch 

 were checked using the method of Simpson et al . (1988b). Mushroom 

 {Agaricus bispora) tyrosinase with an activity of 2,200 units/mg solid was 

 purchased from Sigma Chemical Co. (St. Louis, MO). Russet potatos and Red 

 Delicious apples were purchased from a local supermarket. White shrimp 

 (Penaeus setiferus) and brown shrimp {Penaeus aztecus) were obtained from 

 a local seafood store. Grass prawn or Taiwanese black tiger shrimp 

 {Penaeus monodon) frozen in dry ice was provided by Dr. J. S. Yang, Food 

 Industry Research and Development Institute, Hsinchu, Taiwan, Republic of 

 China. Lobster cuticle, shrimp cephalothorax (head), and potato and apple 

 peels were frozen in liquid nitrogen and ground into a fine powder using 

 a Waring blender. The ground powder was stored at -20°C until needed. 



Extracti on and Purification of Lobster PPn 



Frozen lobster tails were thawed at room temperature. After the 

 cuticle was separated from the flesh, it was frozen in liquid nitrogen and 

 ground into a fine powder in a Waring blender. The cuticle powder was 

 stored at -20°C and used as required. 



PRO was extracted according to the procedure of Simpson et al . 

 (1988a). One part lobster cuticle powder was added to three parts (w/v) 

 0.05 M sodium phosphate buffer (pH 7.2) containing 1 M NaCl and 0.2% Brij 

 35 (Fisher Scientific Co., Orlando, FL). The extract was stirred for 3 hr 

 at 4°C and the suspension was centrifuged at 8,000g (4°C) for 30 min. The 

 supernatant was then dialyzed at 4°C overnight against 3 changes (4L) of 

 0.05 M sodium phosphate buffer (pH 6.5). 



