Thermal Deactivation Kinetics of Pseudomonas fluorescens Lipase Entrapped in AOT/Isooctane Reverse Micelles

Abstract

Thermostability of the lipase (EC 3.1.1.3) was found to be increased by the enzyme-entrapment in 50 mM AOT/isooctane reverse micelles. The half-life (15.75 h) of Pseudomonas fluorescens lipase entrapped in reverse micelles at 70 °C was 9.72- and 11.41-fold longer than those solubilized in a glycerol pool or in 10 mM phosphate buffer (pH 8.0), respectively. The enzyme deactivation model considering a two-step series-type was employed, and deactivation constants for the second step (k₂) at all temperatures were drastically decreased after the lipase was entrapped in reverse micelles. In particular, k₂ (0.0354 h⁻¹) at 70 °C in reverse micelles was 12.33- and 13.14-fold lower than in a glycerol pool or in the phosphate buffer, respectively. The deactivation energies (from k₁, k₂) for the lipase entrapped in the reverse micelles, solubilized in a glycerol pool, or in the aqueous buffer were 7.51, 26.35 kcal/mol, 5.93, 21.08 kcal/mol, and 5.53, 17.57 kcal/mol, respectively.

Design of Raspberry‐Shaped Microcarriers with Adjustable Protrusions and Functional Groups for the Improvement of Lipase Immobilization and Biocatalysis: Environmentally Friendly Esterification of Oleic Acid for Biodiesel

“…After fitting the data, the free and immobilized lipase are accorded with a two‐step series‐type enzyme model [Eq. (1)]: …”

The effect of enzyme loading, alcohol/acid ratio and temperature on the enzymatic esterification of levulinic acid with methanol for methyl levulinate production: a kinetic study

“…The slowdown of reaction rate could be caused by enzyme deactivation, 22,23 product inhibition 24 and attainment of chemical equilibrium 13 as others have demonstrated. Increase in C E can cause high cost even if Y is improved.…”

Microemulsion systems for catalytic reactions and processes

“…16 Further parameters that influence the enzyme activity are the pH value and the temperature. Usually, the enzyme shows highest activity only for one pH value as shown by Park et al 21 and Fei et al 17 Both researchers also investigated enzyme activity as a function of temperature. For temperatures above 40 °C, enzyme denaturation is observed and activity decreases with increasing temperature.…”

“…For temperatures above 40 °C, enzyme denaturation is observed and activity decreases with increasing temperature. However, Park et al 21 showed that the enzyme is less temperature sensitive in w/o-microemulsions, because the surfactant suppresses the interaction between the enzyme and the organic solvent. Even if the reactions are carried out in w/o-microemulsions, different groups have shown that the reaction can be described by applying the Michaelis-Menten kinetics.…”