7451
High sensitivity of binding inhibition to spermine was conferred by a Tyr residue , whereas a His residue favored high potency at acidic pH .
 Chemical: spermine; Chemical: Tyr; Chemical: His
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: spermine; Chemical: Tyr; Chemical: His