Taking these limitations into account, the resulting experimental and calculated activation energies are shown in Tables and and and S10 (PRA). We note that the smaller substrate PRA has much more conformational freedom in the HisA and PriA active sites, which are both evolved to (also) accommodate the larger substrate ProFAR, and is thus capable of sampling a broad number of different conformations at the Michaelis complex, leading to an increased standard error of the mean in comparison to systems where ProFAR is bound to the active site of the these enzymes. and).