. Hence, the value of ∆𝑈 𝑡𝑜𝑡 ,𝑟 ‡ compared to the uncatalyzed reaction is about 10 kcal/mol lower for PchB and about 20 kcal/mol lower for BsCM. The magnitude of ∆𝑈 𝑡𝑜𝑡,𝑟 ‡ is mainly determined by the several partially formed (single and double) bonds in the transition state, which is the reason for why its main contribution comes from