Promiscuous Binding in a Selective Protein: The Bacterial Na+/H+ Antiporter

摘要: The ability to discriminate between highly similar substrates is one of the remarkable properties enzymes. For example, transporters and channels that selectively distinguish various solutes enable living organisms maintain control their internal environment in face a constantly changing surrounding. Herein, we examine detail selectivity most important salt transporters: bacterial Na/H antiporter. Selectivity can be achieved at either substrate binding step or subsequent antiporting. Surprisingly, using both computational experimental analyses synergistically, show per se not sufficient determinant selectively. All alkali ions from Li Cs were able competitively bind antiporter's site, whether protein was capable pumping them not. Hence, propose NhaA's site relatively promiscuous determined later stage transport cycle.