Irreversible high pressure inactivation of beta-galactosidase from Kluyveromyces lactis: comparison with thermal inactivation.
High hydrostatic pressure and high temperature are both shown to induce inactivation of Kluyveromyces lactis beta-galactosidase in deionised water and their respective effects are compared. These two physical parameters lead to similar inactivation kinetics which can be suitably represented by series-type models. The plot of half-lives as a function of pressure is close to the same plot towards temperature. Thus, the same inactivation rate constant can be obtained in two different ways: an increase in pressure at room temperature or an increase in temperature at atmospheric pressure (e.g. 125 MPa at 25 degrees C or 45 degrees C at 0.1 MPa for a kappa 1 value about 28 x 10(-2) min -1). When beta-galactosidase was prepared in 0.1 M potassium phosphate buffer pH 7.3, its stability in extreme conditions of pressure as at high temperature was strongly enhanced. This stabilizing effect of the buffer was essentially attributed to a pH-effect by comparison with the behaviour of the enzyme in a similar buffer but with a 10-fold lower ionic strength.
Cavaille-Lefebvre
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INSA, Centre de Bioingénierie Gilbert Durand (U.M.R. CNRS 5504, L.A. INRA) Complexe Scientifique de Rangueil, Toulouse, France.
Combes
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D001709:Biotechnology; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006874:Hydrostatic Pressure; D007700:Kinetics; D007716:Kluyveromyces / Q000201:enzymology*; D009994:Osmolar Concentration; D001616:beta-Galactosidase / Q000037:antagonists & inhibitors*
D001616:beta-Galactosidase