1438
While many of the structures investigated do not reveal a complete path between the zinc bound water and His - 64 , several others do indicate the presence of a transient connection even when His - 64 is present in its outward conformation .
 Chemical: zinc; Chemical: His; 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: zinc; Chemical: His; Chemical: His