13951
Among the tested systems ( barnase - barstar ( BBS ) , streptavidin - biotin , antibody - antigen , and protein A - immunoglobulin ) , the BBS is notable due to the combination of its high resistance to severe chemical perturbation and unique advantages offered by genetic engineering of this entirely protein - based system .
 Chemical: streptavidin; Chemical: biotin
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: streptavidin; Chemical: biotin