title: Measurement of biochemical affinities with a Gill titration calorimeter.
abstract: A Gill titration calorimeter is evaluated as an instrument to determine in one experiment the equilibrium constant and the enthalpy change of a biochemical reaction. The dimensionless parameter kc (the product of the association equilibrium constant and the concentration of the reagent to be titrated; Wiseman et al., Anal. Biochem. 179, 131-137, 1989) is used to analyze the instrument performance. The analysis of simulated titration data corresponding to a simple model case shows that association equilibrium constants in the 10(2)-10(7) M-1 range may be determined when the kc parameter is between 1 and 1000. In addition we use a Monte Carlo approach to estimate the precision in the thermodynamic parameters of the reaction under study. The relative precision in the calculated constants ranges from 3 to 80% depending on the macromolecule concentration and kc value in the experiment. These results were checked with the study of the reactions of beta-trypsin with its inhibitor and ribonuclease A with cytidine 2'-monophosphate and cytidine 3'-monophosphate.
authors.affiliation: Facultad de Ciencias, Universidad de Granada, Granada, 18071, Spain.
authors.forename: M E
authors.initials: ME
authors.lastname: Harrous
authors.forename: A
authors.initials: A
authors.lastname: Parody-Morreale
mesh_terms: D001665:Binding Sites; D002151:Calorimetry / Q000295:instrumentation / Q000379:methods*; D003568:Cytidine Monophosphate / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism*; D004798:Enzymes / Q000378:metabolism*; D007700:Kinetics; D009010:Monte Carlo Method; D010940:Plant Proteins / Q000378:metabolism; D011485:Protein Binding; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D013816:Thermodynamics; D017186:Titrimetry / Q000379:methods*; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors; D000516:alpha-Amylases / Q000037:antagonists & inhibitors
chemical_list: D004791:Enzyme Inhibitors; D004798:Enzymes; D010940:Plant Proteins; D014361:Trypsin Inhibitors; D012259:Ribonuclease, Pancreatic; D000516:alpha-Amylases; D014357:Trypsin; D003568:Cytidine Monophosphate