Modeling of the thermal behaviour of free β-galactosidase from palm weevil, Rhynchophorus palmarum Linn. (Coleoptera: Curculionidae) larvae using Equilibrium model

Abstract

β-galactosidases are a class of enzyme widely used as biocatalysts in the food, dairy, and fermentation industries. However, due to their biological origin, enhancement of these enzymes is generally necessary. The effect of temperature upon enzymes is a mandatory stage in rational enzyme engineering. The present work was devoted to Rhynchophorus palmarum Linn. β-galactosidase (Rpbgal) as part of the investigation of insect-derived enzymes for biotechnological applications. The thermal behaviour of Rpbgal has been studied in the temperature range 303-353 K by measuring enzymatic activities in presence of oNPG as substrate. Equilibrium model which gives complete and quantitative description of the effect of temperature on enzyme activity has been used to analyze experimental data. A satisfactorily agreement between the calculated results and the experimental data was obtained. The thermodynamic parameters provided by this model were given. Results showed that Rpbgal is relatively stable and active at 323 K. Temperatures over 330 K produce a significant decrease in the enzyme activity. In the temperature range 331 - 339 K, Rpbgal showed the best thermal stability compared to a commercial β-galactosidase from Aspergillus oryzae.