Kinetic and thermodynamic studies of a novel acid protease from Aspergillus foetidus

Abstract

The kinetics of a thermostable extracellular acid protease produced by an Aspergillus foetidus strain was investigated at different pH, temperatures and substrate concentrations. The enzyme exhibited maximal activity at pH 5.0 and 55°C, and its irreversible deactivation was well described by first-order kinetics. When temperature was raised from 55 to 70°C, the deactivation rate constant increased from 0.018 to 5.06h(-1), while the half-life decreased from 37.6 to 0.13h. The results of activity collected at different temperatures were then used to estimate, the activation energy of the hydrolysis reaction (E*=19.03kJ/mol) and the standard enthalpy variation of reversible enzyme unfolding (ΔH°U=19.03kJ/mol). The results of residual activity tests carried out in the temperature range 55-70°C allowed estimating the activation energy (E(*)d=314.12kJ/mol), enthalpy (311.27≤(ΔH°d≤311.39kJ/mol), entropy (599.59≤ΔS(*)d≤610.49kJ/mol K) and Gibbs free energy (103.18≤ΔG(*)d≤113.87kJ/mol) of the enzyme irreversible denaturation. These thermodynamic parameters suggest that this new protease is highly thermostable and could be important for industrial applications. To the best of our knowledge, this is the first report on thermodynamic parameters of an acid protease produced by A. foetidus.

Biochemical characterization and kinetic/thermodynamic study of Aspergillus tamarii URM4634 β‐fructofuranosidase with transfructosylating activity

“…As is known, is directly related to the activation enthalpy of thermal denaturation (Δ), which is the total amount of thermal energy required to denature the enzyme and is related to the number of noncovalent bonds broken during the denaturation process . The positive and large values of Δ estimated for A. tamarii FFase (290.4–290.3 kJ mol −1 ) (Table ) are consistent with the fact that enzyme denaturation is an endothermic process and with its high thermostability.…”

“…44 As is known, E * d is directly related to the activation enthalpy of thermal denaturation (ΔH * d ), which is the total amount of thermal energy required to denature the enzyme and is related to the number of noncovalent bonds broken during the denaturation process. [45][46][47] The positive and large values of ΔH * d estimated for A. tamarii FFase (290.4-290.3 kJ mol −1 ) ( Table 4) are consistent with the fact that enzyme denaturation is an endothermic process and with its high thermostability. It has been proposed that the absorbed thermal energy increases the structural fluctuation in the enzyme structure and thus weakens or disrupts noncovalent bonds that hold it together; therefore, higher values of E * d and ΔH * d indicate stronger intramolecular stabilizing forces and a less extended conformation.…”

Partial Characterization of an Acidic Protease from Rhizopus stolonifer RN-11

“…4 and 5). This was similar to the rhizopuspepsin from Rhizopus oryzae NBRC 4749 [25] and acid protease from Aspergillus foetidus [34], but lower than that of rhizopuspepsins (60°C) from R. chinensis Saito [14] and R. oryzae MTCC 3690 [11]. Fig.…”

ALKALINE PROTEASE PRODUCTION BY Bacillus licheniformis LBA 46 IN A BENCH REACTOR: EFFECT OF TEMPERATURE AND AGITATION

“…Abdel-Naby 2017described a lower E a of 17.31 kJ/mol for alkaline protease from Bacillus stearothermophilus. Souza et al (2015) also found E a (19.03 kJ/mol) for acid protease from Aspergillus foetidus lower than that described in this study. It can be observed that the proteases produced by different microorganisms have different E a values.…”