500
The second series of peptides derives from the endogenous protein kinase C ( PKC ) inhibitor PKI55 , a 55 - amino acid protein , whose synthesis is induced by PKC activation , so that a feedback loop of inhibition is established .
 Chemical: amino acid
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: amino acid