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The phosphoramidate nerve agent tabun inhibits butyrylcholinesterase ( BChE ) and acetylcholinesterase by making a covalent bond on the active site serine .
 Chemical: phosphoramidate; Chemical: tabun; Chemical: serine
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: phosphoramidate; Chemical: tabun; Chemical: serine