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Updated: Jun 27, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Thermodynamic and activation parameters for binding of a pyrene-labeled substrate by the Tetrahymena ribozyme:
Y Li1, P C Bevilacqua, D Mathews
1Department of Chemistry, University of Rochester, New York 14627-0216, USA.
Abstract:
Association and dissociation rates for the pyrene-(pyr)-labeled oligoribonucleotide substrate pyrCUCU binding to the L-21 ScaI group I ribozyme are reported as a function of temperature. Combined with thermodynamic parameters for binding of pyrCUCU to rGGAGAA, the results allow calculation of the activation and thermodynamic parameters for docking of pyrCUCU into the catalytic core of the ribozyme. The activation enthalpy for docking is 22 kcal/mol, much larger than the approximately 4 kcal/mol expected for a diffusion-controlled process. Thus, docking is not diffusion-controlled. The activation and equilibrium entropies for docking are favorable at 21 and 37 eu, respectively. The results suggest the rate-limiting step and the driving force for docking may involve desolvation of RNA functional groups or of Mg2+ ions.
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