Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9694207 | Thermochimica Acta | 2005 | 7 Pages |
Abstract
The enzymatic hydrolysis of phenyl acetate, catalysed by arylesterase/paraoxonase (EC 3.1.8.1) was studied at 37â° C in Tris buffer, pH 8, by spectrophotometry and flow microcalorimetry, using an enzyme purified from human serum. After correction for buffer protonation and product ionization, the hydrolysis reaction was found to be slightly endothermic, with ÎH=8.2âkJâmolâ1. Microcalorimetric data were analysed with the integrated Michaelis equation to give the kinetic parameters of the enzyme: Michaelis constant Km=2.4âmM, catalytic constant kcat=2.4Ã103âsâ1, bimolecular rate constant ks=1.0Ã106âMâ1âsâ1. These results were in agreement with the spectrophotometric method. This study confirms the usefulness of microcalorimetry in the field of enzyme kinetics.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
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Authors
Jean Debord, Michel Harel, Jean-Claude Bollinger, Bernard Verneuil, Louis Merle, Thierry Dantoine,