3340
The results reveal that the imidazole nitrogen atom of GlcNAcstatin has shown a better interaction with the active site of Clostridium perfringens in its protonated form , which is compatible with a substrate - assisted reaction mechanism involving two conserved aspartate residues ( 297 and 298 ) .
 imidazole, nitrogen, GlcNAcstatin, aspartate
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 imidazole, nitrogen, GlcNAcstatin, aspartate