21732
It is proposed that this conserved His residue might play a key role both in formation of active photoprotein and in Ca ( 2 + ) - triggering of the bioluminescence reaction .
 Chemical: His; 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: His, Ca ( 2 + ) 
Answer:
 Chemical: His; Chemical: Ca ( 2 + )