21728
Ca ( 2 + ) - regulated photoproteins use a noncovalently bound 2 - hydroperoxycoelenterazine ligand to emit light in response to Ca ( 2 + ) binding .
 Chemical: Ca ( 2 + ); Chemical: 2 - hydroperoxycoelenterazine; Chemical: Ca ( 2 + )
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: Ca ( 2 + ), 2 - hydroperoxycoelenterazine, Ca ( 2 + ) 
Answer:
 Chemical: Ca ( 2 + ); Chemical: 2 - hydroperoxycoelenterazine; Chemical: Ca ( 2 + )