ADP-inhibited structure of non-catalytic site-depleted FF-ATPase from thermophilic Bacillus sp. PS-3.

The F domain of FF-ATP synthases/ATPases (FF) possesses three catalytic sites on the three αβ interfaces, termed αβ, αβ, and αβ, located mainly on the β subunits. The enzyme also has three non-catalytic ATP-binding sites on the three αβ interfaces, located mainly on the α subunits. When ATP does not bind to the non-catalytic site, FF becomes significantly prone to ADP inhibition, ultimately resulting in the loss of ATPase activity.