Guanosine binds to the Tetrahymena ribozyme in more than one step, and its 2'-OH and the nonbridging pro-Sp phosphoryl oxygen at the cleavage site are required for productive docking.
Profenno LA, Kierzek R, Testa SM, Turner DH, Biochemistry, 1997 Oct 14 - link

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