2808
Therefore , we designed three HBPs by deleting some N - and C - terminal residues of HuBChE by maintaining the folds of the active site core that includes the three active site residues ( S198 , E325 , and H438 ) .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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