  Allosteric regulation is often viewed as thermodynamic in nature. However
protein internal motions during an enzymatic reaction cycle can be slow hopping
processes over numerous potential barriers. We propose that regulating
molecules may function by modifying the nonequilibrium protein dynamics. The
theory predicts that an enzyme under the new mechanism has different
temperature dependence, waiting time distribution of the turnover cycle, and
dynamic fluctuation patterns with and without effector. Experimental tests of
the theory are proposed.
