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The carbonyl oxygen of Gly48 showed two alternative conformations in all structures likely due to the snug fit of the large tris - THF group in the S2 subsite in agreement with high antiviral efficacy of 1 on resistant virus .
 Chemical: carbonyl; Chemical: oxygen; Chemical: tris - THF
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: carbonyl; Chemical: oxygen; Chemical: tris - THF