2659
The binding mechanism involves residue ( A beta ) K28 ( similar to ( ATX ) R32 ) which forms cation / pi interactions in the acetylcholine binding site , and residues ( A beta ) G29 - ( A beta ) I32 [ GAII ] ( similar to ( ATX ) G33 - ( ATX ) I36 [ GTII ] ) which form an intermolecular beta - sheet with residues ( alpha 7 ) F189 - ( alpha 7 ) E191 of AChR .
 Chemical: acetylcholine
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: acetylcholine