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the inhibitor, kojic acid (5-hydroxy-2-hydroxymethyl-7-pyrone) . Since the 

 conformational structures of these fungal, plant and crustacean PPOs has 

 not been well documented, this study was undertaken to elucidate whether 

 conformational differences exists among these PPOs using immunological 

 techniques and circular dichroism spectropolarimetry. 



Materials and Methods 



Fresh Florida spiny lobster {Panuh'rus argus) tails obtained from 

 the Whitney Marine Laboratory at Marineland, FL, were transported in ice 

 to the laboratory and stored at -20°C. Mushroom {Agan'cus bispora) ' . >> 

 tyrosinase with an activity of 2,200 units/mg solid was purchased from r . 

 Sigma Chemical Co. Russet potato was purchased from a local supermarket. 

 White shrimp {Penaeus setiferus) and brown shrimp {Penaeus aztecus) were 

 obtained from a local seafood store. Lobster cuticle, shrimp < 

 cephalothorax (head), and potato peel were each frozen in liquid nitrogen ?». 

 and ground into a fine powder using a Waring blender. The individual ■ ., 

 ground powder was stored at -20°C until needed. 



Extraction of Mushroom. Potato. Lobster, and Shrimp PPO 



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

 (1988a). One part ground 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. 

 The extract was stirred for 5 min 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 of 4L 0.05 M sodium phosphate buffer (pH 6.5). 



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