9424
A library of protein domain variants can be generated by mutagenic PCR , expressed on the surface of bacteriophage M13 , and subjected to heat , such that the unfolded forms of the domain , showing reduced or no binding activity , are lost during subsequent affinity selection , whereas variants that still retain binding to their target are selected and enriched with each subsequent round of affinity selection .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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