The energetics of both processes, when compared to the respective starting points (E apo ) suggest that the proR-TS apo is associated with a higher energy barrier (99.8 kJ/mol) than the proS-TS apo (80.6 kJ/mol) (Table , Table -S9). The latter value however omits an additional required energy input of 86.8 kJ/mol for the conformational shift from proR E apo to proS E apo .