Triggering enzymatic activity with force.

Integrating single molecule force spectroscopy with fluorescence-based techniques allows the manipulation of an enzyme with a periodic stretching and relaxation protocol while simultaneously monitoring its catalytic activity. After releasing the stretching force we observe a higher probability for enzymatic activity at a time of 1.7 s. A detailed theoretical analysis reveals that the relaxation from the force-induced enzyme conformation to the observed active conformation follows a cascade reaction with several steps and a free energy difference of at least 8 k(B)T. Our study clearly points out the direct influence of force on enzymatic activity and opens up a new way to study and manipulate (bio)catalytic reactions at the single molecule level.