Ionic and covalent immobilization of glucose isomerase of thermophilic Anoxybacillus gonensis on DEAE-sepharose

Abstract

High fructose corn syrup (HFCS), which is produced by the conversion of one sugar into another (glucose to fructose), has a marketing value. Hence, different glucose isomerases [(GI) (D-xylose ketol isomerase, EC 5.3.1.5)] isolated from different sources (macro-and microorganisms) were researched until today. In addition, the cost reduction of GI production for industrial applications has been investigated and applied with different techniques. Enzyme immobilization approaches have prominent features because they allow enzymes to be used repeatedly. In the current study, Anoxybacillus gonensis G2T glucose isomerase (AgoGI) (wild type) were immobilized with ionic and covalent binding on DEAE-sepharose matrix. Afterward, kinetic and biochemical parameters of the immobilized enzymes were evaluated. The pH and temperature parameters, in which the ionic and covalent immobilized enzymes showed the best activity, were determined as 6.50 and 85 °C, respectively. The kinetic data (Vmax and Km) of ionic bound AgoGI on DEAE-sepharose were 4.85±2.09 μmol/min/mg protein and 130,57±5,42 mM, as covalent immobilized AgoGI on the same matrix were 40.51± 0.81 μmol/min/mg protein µmol/min and 127,28±2,96 mM, respectively. Consequently, the usage of DEAE-sepharose for both covalent and ionic immobilization as immobilization matrix did not exhibit any negative effects on biochemical and kinetic parameters of glucose isomerase. Therefore, immobilized AgoGI on DEAE-sepharose was an excellent and promising tool for HFCS production.