Immobilization of endoglucanase Cel9A on chitosan nanoparticles leads to its stabilization against organic solvents: the use of polyols to improve the stability

Abstract

The immobilization of enzymes improves their stability in non-conventional media such as organic solvents. In this work, the effects of solvents (DMSO, methanol, ethanol, and n-propanol) on the endoglucanase Cel9A activity and stability were studied. Then, the enzymes were stabilized by its immobilization on chitosan nanoparticles and also using polyols (sorbitol and glycerol) against organic solvents. The SEM results illustrated that the chitosan nanoparticles had about 40 nm diameter. The results indicated that the organic solvents, especially n-propanol, decreased the activity of the free and immobilized enzymes. The reduced activity of the immobilized enzyme was less than that of the free enzyme. Our studies about the enzymes' stability showed that the free and immobilized enzymes in hydrophobic solvents (with high log P) had the lowest stability compared to other solvents as we observed the half-life of the free enzyme in n-propanol solvent was 2.84 min, and the half-life of the immobilized enzyme was 4.98 min in n-propanol and ethanol solvents 4.50 min. Analysis of the combinatory effects of polyols (sorbitol and glycerol) and the solvents on the stability revealed that sorbitol and glycerol had the most stabilizing effect on the free enzyme in hydrophilic (DMSO) and hydrophobic (n-propanol) solvents, respectively. However, the stabilizing effects of polyols in the immobilized enzyme were independent of the solvents' hydrophobicity (or log P) due to the hydrophilic properties of chitosan nanoparticles. Therefore, one can conclude that the physiochemical properties of nanoparticles (such as hydrophilicity) influence the stabilizing effects of polyols on immobilized enzyme.

Chitosan Nanoparticles Loaded with Quercetin and Valproic Acid: A Novel Approach for Enhancing Antioxidant Activity against Oxidative Stress in the SH-SY5Y Human Neuroblastoma Cell Line

“…In synthesizing NPs, pH, ultrasonic bath soaking time, stirring speed, and duration were considered. In our study, when FE-SEM (Figure 1) and TEM (Figure 2) images were examined, it was seen that NP1 and NP3 were nearly spherical in shape [31], and NP2 and NP4 were strip-like structures [32]. The FE-SEM and TEM images of the NPs synthesized in our study are similar to those of NPs containing Que and VPA in the literature [32][33][34][35][36].…”

Enhancing Enzyme Stability and Functionality: Covalent Immobilization of Trypsin on Magnetic Gum Arabic Modified Fe3O4 Nanoparticles

“…The immobilized trypsin exhibited a lower V max (10.50 µmol/mg.min for the immobilized trypsin compared to 20.00 µmol/mg.min for the free trypsin) and a higher K m than free enzyme (2.00 g/L for the free enzyme to 3.65 g/L compared to the immobilized enzyme). Enzyme immobilization rigidi es the enzyme structure and reduces its exibility, a factor crucial for enzyme activity [52][53][54][55][56]. Thus, the decrease in V max and the increase in K m for immobilized trypsin could be correlated with the enhanced rigidity of the enzyme and the chemical characteristics of gum Arabic (including the hydrophilic property of the support and the slight hydrophobicity of the substrate).…”