Carboxymethyl tamarind gum–silica nanohybrids for effective immobilization of amylase

Carboxymethyl tamarind gum initiated and catalyzed sol–gel polymerization of tetramethoxysilane produced polysaccharide nanohybrids which were efficient in immobilizing α-amylase for starch hydrolysis. The nanohybrids have been characterized by FTIR, XRD, SEM, TGA and BET analyses. The optimum nanohybrid sample (C) in terms of α-amylase immobilization was synthesized when water (H2O), tetramethoxysilane (TMOS) and methanol (MeOH) were used in 17:1:1 ratio at fixed template amount (0.5 g of carboxymethyl tamarind gum). Enzyme immobilization efficiency of “C” was further enhanced on calcination in nitrogen atmosphere, the optimum calcination temperature being 400 °C (C4). Nanohybrid (C4) impregnated with 40 μg of α-amylase was used for hydrolyzing soluble potato starch to glucose syrup at different temperatures, pH values and enzyme concentrations as these parameters affect the kinetics of the studied reaction. The optimum pH and temperature for the hydrolysis reaction were pH 5 and 40 °C, respectively. The kinetic parameters, Km (4.261 mg mL−1) and Vmax (2.55 mol mL−1 min−1) for the immobilized amylase were found favorable over the respective values obtained for the free enzyme (Km = 6.269 mg mL−1, Vmax = 1.53 mol mL−1 min−1). The enzyme activity remained unchanged up to 90 days inside the nanohybrid matrix. The immobilization at the nanohybrid improved the overall stability, affinity and catalytic property of α-amylase.

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► Carboxymethyl tamarind gum significantly catalyzes the dehydroxylation polymerization of tetramethoxysilane.
► It acts as template to furnish novel material (CMT–silica) which is very effective for immobilization of amylase.
► On immobilization at CMT–silica, affinity, catalytic activity and thermal stability of amylase improved significantly.
► Enzyme immobilized at CMT–silica is stable and easily recyclable.