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Consistent with a gating - induced movement that disrupts the Glu167 / Arg290 salt bridge , a comparison of the closed and open rat P2X2 receptor models revealed a significant rearrangement of the protein backbone and the side chains of the Glu167 and Arg290 residues during the closed - to - open transition .
 Chemical: Glu167; Chemical: Arg290; Chemical: Glu167; Chemical: Arg290
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: Glu167, Arg290, Glu167, Arg290 
Answer:
 Chemical: Glu167; Chemical: Arg290; Chemical: Glu167; Chemical: Arg290