Abstract

The thermodynamic or conformational stability of psychrotroph lipases and proteases, measured as the Gibbs free energy difference (ΔG) between the native and denatured enzymes, were estimated from enzyme temperature-activity profile data. ΔG estimates of 8–10 kJ/mol and 16–17 kJ/mol were obtained for psychrotroph-derived lipases and proteases, respectively. Pseudomonas fluorescens strain AR-11 protease was unusually thermolabile (ΔG = 3·0–7·6 kJ/mol). These values were compared with values for some mesophilic and thermophilic enzymes and the possible relationship of ΔG to psychrotrophic enzyme heat-resistance is discussed.