27424
We describe a new cell - free protein synthesis ( CFPS ) method for site - specific incorporation of non - natural amino acids ( nnAAs ) into proteins in which the orthogonal tRNA ( o - tRNA ) and the modified protein ( i . e . the protein containing the nnAA ) are produced simultaneously .
 amino acids
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 amino acids