1791
The homology demonstrated by the comparison of sequences , with zinc - dependent metalloproteinases , as well as the metal chelant effects on , confirmed that the colombienases were metalloproteinases , particularly to alpha - fibrinogenases belonging to the P - I class of SVPMs ( 20 - 30 kDa ) , which contain only the single - domain proteins .
 Chemical: zinc
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