Immobilization of α‐amylase via adsorption onto bentonite/chitosan composite: Determination of equilibrium, kinetics, and thermodynamic parameters

Abstract

Immobilization of α‐amylase onto bentonite/chitosan (BC) composite was studied via adsorption. The composite was characterized by FTIR, SEM, and surface area measurements. The effect of different factors such as, pH, temperature, initial enzyme concentration, and various thermodynamic parameters was determined. The maximum α‐amylase adsorption capacity of the BC composite was determined as 64 mg/g at 0.8 mg/mL enzyme concentration. The activity of the immobilized enzyme was measured under varying experimental conditions. The highest enzyme activity for free and immobilized enzyme was determined at 30 and 35°C in 0.1 M phosphate buffer at pH 7.0. The effect of substrate concentration on enzyme activity of free and immobilized enzymes showed a good fit to the Lineweaver–Burk plots. Michaelis constant, Km, for the immobilized α‐amylase was found to be higher than for the free enzyme. The adsorption isotherm was modeled by the Langmuir equation.

Immobilization of α-amylase via adsorption on magnetic particles coated with polyaniline

“…The Langmuir adsorption capacity, Q max was 55.56/100 mg support, while the Freundlich adsorption capacity, K was 8.88/100 mg support. The 1/ n value is a scale of the surface heterogeneity and may have a value between 0 and 1, becoming more heterogeneous as its value gets closer to zero . The results show that the Langmuir adsorption model fitted the experimental data better ( R 2 = 0.963) than the Freundlich model ( R 2 = 0.899).…”

“…The adsorption of enzymes on solid supports is the oldest, simplest, and easiest method of immobilization. The simplicity of the procedure, the cost, and the fact that the initial activity of the enzyme is maintained to a considerable degree make this method suitable in commercial production .…”

Structural identification of alkyl glycosides obtained from the conversion of canna starch by immobilized α‐amylase from Aspergillus oryzae

“…The effects of the enzyme concentration (mg/mL), the volume of loaded enzyme (µL/bead), the activation time (h), and the incubation time on the adsorption of α‐amylase onto the chitosan beads were investigated. The adsorption process was monitored by following the decrease of the α‐amylase concentration by ultraviolet absorbance at 280 nm . The adsorption efficiency of α‐amylase onto the beads was determined as follows: where q is the percentage of α‐amylase adsorbed onto the beads (mg/100 mg), C 0 and C are the initial and final α‐amylase contents, respectively (mg).…”

“…However, the variation of the optimal pH value upon immobilization was different. In previous studies [22,27], free and immobilized a-amylases had optimal activities at the same pH value although the enzymatic stability in relation to the change of the pH value was improved for the immobilized form. The observed discrepancy might be due to the structural reconstruction of the enzyme molecules.…”

Adsorption of cellulase on poly(2-hydroxyethyl methacrylate) cryogels containing phenylalanine

“…Protein adsorption is very complicated process driven by different protein-surface forces, such as hydrophobic, electrostatic, and ionic interactions; van der Waals forces; or hydrogen bonds; and the temperature dependency of these forces is different from each other. 34,35 Effect of temperature on the adsorption process was studied at five different temperatures (5-40 • C). As seen in Figure 5, maximum cellulase adsorption was observed at 25 • C. It was observed that the maximum cellulase adsorption onto p(HEMA-MAPA) cryogel was increased slightly (8.9%) by increasing temperature from 5 to 25…”