8689
Based on the known Sap2 - substrate specificity data and X - ray analyses of Sap / inhibitor complexes , three libraries of inhibitors were designed and synthesized by modifying the structure of pepstatin A , a common non - selective aspartic proteinase inhibitor , at the P3 , P2 , or P2 ' position .
 Chemical: pepstatin A
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: pepstatin A