Riboswitch classes in present study.

Thermodynamic and kinetic control of ligand binding is defined in the Introduction. Briefly, if the time required for equilibrium between ligand and aptamer is equal to or less than the amount of time it takes for the RNA to be fully transcribed, the switch will approximate thermodynamic (equilibrium) control. However, if the time required for RNA-ligand equilibrium is long, the switch is under kinetic control. *KD values listed are for the aptamer sequence at 298K, but ranges depend on experimental conditions. ‡Investigators proposed that these riboswitches could function under thermodynamic control if there were transcriptional pause sites of a couple seconds or changes from standard temperature. §These riboswitches are known to require pseudoknot interactions for activity.