Thermodynamic and activation parameters for binding of a pyrene-labeled substrate by the Tetrahymena ribozyme: docking is not diffusion-controlled and is driven by a favorable entropy change.
Li Y, Bevilacqua PC, Mathews D, Turner DH, Biochemistry, 1995 Nov 7 - link

Fluorescence-detected stopped flow with a pyrene labeled substrate reveals that guanosine facilitates docking of the 5' cleavage site into a high free energy binding mode in the Tetrahymena ribozyme.
Bevilacqua PC, Li Y, Turner DH, Biochemistry, 1994 Sep 20 - link