5262
We improved upon these activities either by substituting a tryptophan ( F347W ) near the putative active site residues for enhanced substrate binding or by reducing a bulky group ( Y71A ) at the periphery of the putative enzyme active site .
 Chemical: tryptophan
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: tryptophan