16898
The case study of porphobilinogen synthase ( PBGS ) illustrates how such an equilibrium holds lessons for disease mechanisms , drug discovery , understanding drug side effects , and identifying proteins wherein drug discovery efforts might focus on quaternary structure dynamics .
 porphobilinogen
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 porphobilinogen