29833
Primary kinetic isotope effects from substrate conversion measurements ( k ' obs ( ( H ) ) / k ' obs ( ( D ) ) = 3 . 3 +/- 0 . 3 ) and from initial rate analysis ( k2 ( ( H ) ) / k2 ( ( D ) ) = 2 . 3 +/- 0 . 4 ) indicate that a N - H bond is broken in the turnover - limiting and irreversible step of the catalytic cycle .
 Chemical: N - H
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: N - H