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In this work a summary of their use as optimal inhibitors of physiologically relevant serine and cysteine proteases is given with a particular emphasis on recently established SAR studies .
 Chemical: serine; Chemical: cysteine
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: serine; Chemical: cysteine