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Comparative properties of A beta 1 - 42 , A beta 11 - 42 , and [ Pyr (1) (1) ] A beta 11 - 42 generated from O - acyl isopeptides .
 Chemical: O - acyl
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: O - acyl