“…For a given system and function x (e.g., a folded RNA sequence that binds to guanosine triphosphate GTP), and degree of function E x (e.g., the RNA-GTP binding energy), functional information is I(E x ) = − log 2 [F(E x )], where F(E x ) is the fraction of all possible configurations of the system [14,[32][33][34]. Functional information, for example, analyzes RNA structures that bind target ligands and RNA structures that catalyze specific reactions.…”