92 



Gleeson, Whitney Marine Laboratory, Marineland, FL, and transported in ice 

 to the laboratory. Fresh, nonsulfited white shrimp {Penaeus setiferus) 

 was obtained from a local seafood store. Grass prawn {Penaeus monodon) 

 frozen in dry ice was provided by Dr. J. S. Yang, Food Industry Research 

 and Development Institute, Hsinchu, Taiwan, Republic of China. 



Extraction and Purification of Potato PRO 



Potato PRO was extracted following the methods of Patil and Zucker 

 (1965) with slight modification. Potato peel (130 g) was suspended 

 overnight in 3 volumes of cold acetone (w/v, -15°C). Frozen tissue was 

 macerated in a Waring blender with 2 volumes of cold acetone (w/v), and 

 the residue obtained following filtration was homogenized again with cold 

 acetone. After centrifugation at 2,5005 (4°C) for 20 min, the precipitate 

 was collected and dried at this temperature. Dried powder was suspended 

 and stirred for 10 min in 50 mL of 0.02 M acetate buffer (pH 5.7) and then 

 poured through cheesecloth. The filtrate was centrifuged at 2,500g (4°C) 

 for 20 min and the supernatant was treated with 1.5 volumes (v/v) of cold 

 acetone (-15°C). The precipitate was dissolved in 40 mL of 0.02 M acetate 

 buffer (pH 5.7), and then was treated again with an equal volume of cold 

 acetone. The acetone-precipitate was dissolved in 0.01 M acetate buffer 

 (pH 5.7) to make a 0.5% (w/v) solution. After removing brown precipitate 

 by centrifugation, one volume of cold acetone was added to the 

 supernatant. The mixture was centrifuged again at 2,500g (4°C) for 20 min 

 and the precipitate was redissolved in 0.01 M acetate buffer (pH 5.7). 

 Ammonium sulfate precipitation between and 60% saturation was obtained 

 by centrifugation at 2,500g (4°C) for 20 min. The ammonium sulfate- 



