20464
The first series comprises substrate analogue inhibitors containing a 4 - amidinobenzylamide moiety in P1 position , whereby some of these analogues possess inhibition constants around 20 nM .
 Chemical: 4 - amidinobenzylamide
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
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Answer:
 Chemical: 4 - amidinobenzylamide