Modifying Thermostability and Reusability of Hyperthermophilic Mannanase by Immobilization on Glutaraldehyde Cross-Linked Chitosan Beads

Abstract

In the current study, the purified β-mannanase (Man/Cel5B) from Thermotoga maritima was immobilized on glutaraldehyde cross-linked chitosan beads. The immobilization of Man/Cel5B on chitosan beads was confirmed by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. After immobilization, the protein loading efficiency and immobilization yield were found to be 73.3% and 71.8%, respectively. The optimum pH for both free and immobilized enzymes was found to be pH 5.5. However, the optimum temperature of immobilized Man/Cel5B increased by 10 °C, from 85 °C (free Man/Cel5B) to 95 °C (Immobilized). The half-life of free and immobilized enzymes was found to be 7 h and 9 h, respectively, at 85 °C owing to the higher thermostability of immobilized Man/Cel5B. The increase in thermostability was also demonstrated by an increase in the energy of deactivation (209 kJmol−1) for immobilized enzyme compared to its native form (92 kJmol−1), at 85 °C. Furthermore, the immobilized Man/Cel5B displayed good operational stability as it retained 54% of its original activity after 15 repeated catalytic reactions concerning its free form.

Covalent Immobilisation of an Aspergillus niger Derived Endo-1,4-β-Mannanase, Man26A, on Glutaraldehyde-Activated Chitosan Nanoparticles for the Effective Production of Prebiotic MOS from Soybean Meal

“…Several new peaks were formed, 2θ = 18.032 2b). The addition of new peaks confirms the strong binding of the endo-1,4-β-mannanase to the glutaraldehyde activated chitosan nanoparticles, like what was previously seen in literature [49].…”

“…The immobilised enzyme's affinity for the substrate (as shown by the K M ) was significantly higher than that of the free enzyme. This result was previously experienced by [49]. It was hypothesised to be due to an improved orientation of the enzyme, increasing accessibility to the active site by the substrate.…”

Immobilization of Xylanase into Zeolitic Imidazolate Framework-67 (ZIF-67) and Manganese-Doped ZIF-67 (Mn/ZIF-67): A Comparison Study

“…Thus, the immobilization process provides an energy saving advantage, which makes the enzyme more economically valuable for industrial uses [57]. On the other hand, the decrease in E a also indicates a lower sensitivity to temperature and a higher stability for the active site of the immobilized enzyme [56,57]. Fig.…”

“…E a indicates the energy that must be exceeded to convert the substrate into a product. This decrease in E a observed for immobilized enzymes means that the enzyme has to cross a lower energy barrier to form a transition state complex with its substrate for hydrolysis to products compared to its free form [56,57]. Thus, the immobilization process provides an energy saving advantage, which makes the enzyme more economically valuable for industrial uses [57].…”

“…This decrease in E a observed for immobilized enzymes means that the enzyme has to cross a lower energy barrier to form a transition state complex with its substrate for hydrolysis to products compared to its free form [56,57]. Thus, the immobilization process provides an energy saving advantage, which makes the enzyme more economically valuable for industrial uses [57]. On the other hand, the decrease in E a also indicates a lower sensitivity to temperature and a higher stability for the active site of the immobilized enzyme [56,57].…”