Related Experiment Video
Updated: Jul 15, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Thermodynamic parameters for the association of fluorinated benzenesulfonamides with bovine carbonic anhydrase II
Vijay M Krishnamurthy1, Brooks R Bohall, Chu-Young Kim
1Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.
Abstract:
This paper describes a calorimetric study of the association of a series of seven fluorinated benzenesulfonamide ligands (C6H(n)F(5-n)SO2NH2) with bovine carbonic anhydrase II (BCA). Quantitative structure-activity relationships between the free energy, enthalpy, and entropy of binding and pKa and log P of the ligands allowed the evaluation of the thermodynamic parameters in terms of the two independent effects of fluorination on the ligand: its electrostatic potential and its hydrophobicity. The parameters were partitioned to the three different structural interactions between the ligand and BCA: the Zn(II) cofactor-sulfonamide bond (approximately 65% of the free energy of binding), the hydrogen bonds between the ligand and BCA (approximately 10%), and the contacts between the phenyl ring of the ligand and BCA (approximately 25%). Calorimetry revealed that all of the ligands studied bind in a 1:1 stoichiometry with BCA; this result was confirmed by 19F NMR spectroscopy and X-ray crystallography (for complexes with human carbonic anhydrase II).
Related Concept Videos
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility
Temporary attractive forces like dispersion are present in all molecules, whether they are polar or nonpolar. They...
Solubility Equilibria: Overview
Solubility is important in biological and environmental processes. A notable...
Electrophilic Aromatic Substitution: Sulfonation of Benzene
Physical Properties of Carboxylic Acid Derivatives
Among the carboxylic acid derivatives, the boiling points of acid chlorides and esters are very similar and are the lowest in the series. Acid anhydrides have slightly higher boiling...
Amines to Sulfonamides: The Hinsberg Test
Generally, a primary amine reacts with the Hinsberg reagent to produce an N-substituted benzenesulfonamide. The electron-withdrawing sulfonyl...

