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The calculated barrier is 8 . 3 kcal / mol higher than that for GSH attack , in line with the observed chemoselectivity of the enzyme , which manages to catalyze the addition of GSH in the presence of water molecules around its active site .
 Chemical: GSH; Chemical: GSH
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: GSH; Chemical: GSH