On the relationship between efficiency and cooperativity in multi-subunit molecular machines

Two key properties of machines are the extent of coordination between their moving parts and their efficiencies. Here, we analyze how the extent of coordination, as reflected in cooperativity between subunits in an oligomeric molecular machine, affects its efficiency. The efficiency is found to increase in a non-linear fashion with increasing cooperativity. In the case of a given cooperativity, efficiency increases when the allosteric constant, that is, the energy difference between the two apo states of the machine, increases or when the binding energy for the high affinity state increases but not both. These results highlight design principles that can guide strategies for increasing machine efficiency.