69 



Conclusion 



Differences in the percentage of secondary structure (a-helix, 

 ^-sheet, ^-turn, and random coil) among polyphenol oxidases from mushroom, 

 potato, and crustacean were revealed by spectropolarimetric analysis. 

 Using competitive ELISA technique, white shrimp and brown shrimp PPOs were 

 shown to share more antigenic determinants similar to that of lobster PPO 

 than potato and mushroom PPOs when these enzymes were tested against anti- 

 lobster PPO antibody. This result was correlated to the previous finding 

 that crustaceans PPO had higher percentage of a-helix than that of potato 

 and mushroom PPOs. 



