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However , in a variation of this assay in which the protease is omitted , the mutant enzymes exhibited substantial levels of prolyl isomerase activity ( 5 - 20 % of wild - type ) , revealing that these mutations confer sensitivity to protease digestion and that the classic in vitro assay for prolyl isomerase activity may be misleading .
 GENE: prolyl isomerase; GENE: prolyl isomerase
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 GENE: prolyl isomerase; GENE: prolyl isomerase