172 

 Protein patterns of CO^-treated and nontreated lobster PPO from 

 acrylamide gel also verified the mass balance (Figure 38). For lobster 

 PPO, the combined protein patterns of the supernatant and the pellet 

 portions matched those of the non-treated PPO. These results indirectly 

 suggest that high pressure CO^ treatment could bring about precipitation 

 of protein molecules and thus causes PPO inactivation. 



Pol yacryl amide Gel Tsnpl ectric Fnrii<:inq nf rn tr°_^trd 



PPO 



The lEF gel patterns showed that the protein band of nontreated and 

 CO^ (1 atm)-treated PPO groups were at the same position (Figure 39) and 

 the pi value was determined as 6.0. Thus. CO, (1 atm) treatment does not 

 alter the electrical properties of the PPO molecule. 



Untreated lobster, brown shrimp, and potato PPO only showed one 

 protein band with an isoelectric point (pi) of 6.0 on the focused gel. 

 Upon treatment with high pressure CO,, the lobster, brown shrimp, and 

 potato PPO showed several protein bands on lEF gel including one with a pi 

 of 6.2 (Figure 40). Therefore, high pressure CO, treatment might cause 

 disintegration of the PPO molecule. 



Spectropolarimetri c Ana l ys is of Hioh PrP..i.ro rn . .treated PPn - ; 



CD spectra at the far UV range for control and high pressure CO,- 

 treated lobster, brown shrimp, and potato PPO are given in Figures 41, 42, 

 and 43, respectively. The negative ellipticity between 207 and 220 nm of 

 controls was quite different from those of CO,-treated PPO. CO,-treatment 

 caused changes in the secondary structures (a-helix, ^sheet, ^-turn, and 

 random coil) (Table 11). Lobster and brown shrimp PPO showed the most 



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X-S 



