101. Expression optimization and characterization of a novel amylopullulanase from the thermophilic Cohnella sp. A01.
- Author
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Hasani F, Tarrahimofrad H, Safa ZJ, Farrokhi N, Karkhane AA, Haghbeen K, and Aminzadeh S
- Subjects
- Hydrogen-Ion Concentration, Kinetics, Cloning, Molecular, Gene Expression, Starch metabolism, Starch chemistry, Escherichia coli genetics, Substrate Specificity, Glucans metabolism, Glucans chemistry, Bacterial Proteins genetics, Bacterial Proteins chemistry, Bacterial Proteins metabolism, Glycoside Hydrolases genetics, Glycoside Hydrolases chemistry, Glycoside Hydrolases metabolism, Enzyme Stability, Temperature
- Abstract
Amylopullulanase (EC. 3.2.1.41/1) is an enzyme that hydrolyzes starch and pullulan, capable of breaking (4 → 1)-α and (6 → 1)-α bonds in starch. Here, the Amy1136 gene (2166 base pairs) from the thermophilic bacterium Cohnella sp. A01 was cloned into the expression vector pET-26b(+) and expressed in Escherichia coli BL21. The enzyme was purified using heat shock at 90 °C for 15 min. The expression optimization of Amy1136 was performed using Plackett-Burman and Box-Behnken design as follows: temperature of 26.7 °C, rotational speed of 180 rpm, and bacterial population of 1.25. The Amy1136 displayed the highest activity at a temperature of 50 °C (on pullulan) and a pH of 8.0 (on starch) and, also exhibited stability at high temperatures (90 °C) and over a range of pH values. Ag
+ significantly increased enzyme activity, while Co2+ completely inhibited amylase activity. The enzyme was found to be calcium-independent. The kinetic parameters Km , Vmax , kcat , and kcat /Km for amylase activity were 2.4 mg/mL, 38.650 μmol min-1 mg-1 , 38.1129 S-1 , and 0.09269 S-1 mg mL-1 , respectively, and for pullulanase activity were 173.1 mg/mL, 59.337 μmol min-1 mg-1 , 1.586 S-1 , and 1.78338 S-1 mg mL-1 , respectively. The thermodynamic parameters Kin , t1/2 , Ea# , ΔH# , ΔG# and ΔS# were calculated equal to 0.20 × 10-2 (m-1 ), 462.09 (min), 16.87 (kJ/mol), 14.18 (kJ/mol), 47.34 (kJ/mol) and 102.60 (Jmol K-1 ), respectively. The stability of Amy1136 under high temperature, acidic and alkaline pH, surfactants, organic solvents, and calcium independence, suggests its suitability for industrial applications., Competing Interests: Declaration of competing interest Authors confirm that there are no potential conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)- Published
- 2024
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