The thermal stability of the Fusarium solani pisi cutinase as a function of pH

Abstract

We have investigated the thermal stability of the Fusarium solani pisi cutinase as a function of pH, in the range from pH 2-12. Its highest enzymatic activity coincides with the pH-range at which it displays its highest thermal stability. The unfolding of the enzyme as a function of pH was investigated bymicrocalorimetry. The ratio between the calorimetric enthalpy (ΔH cal) and the van′t Hoff enthalpy (ΔHv) obtained, is far from unity, indicating that cutinase does not exhibit a simple two state unfolding behaviour. The role of pH on the electrostatic contribution to the thermal stability was assessed using TITRA. We propose a molecular interpretation for the pH-variation in enzymatic activity. © 2001 Hindawi Publishing Corporation.