Co-immoblization of glucoamylase and glucose isomerase as cross-linked enzyme aggregate and its characterization

In this study, glucoamylase (GA) and glucose isomerase (GI) were co-immobilized as cross-linked enzyme aggregates (combi-CLEA(GA+GI)). Glutaraldehyde and polyglutaraldehyde were used as cross-linking agents. The hydrolysis of starch using different combination of two free enzymes (GA+GI) and combi CLEA (GA+GI) in ionic liquids ([Bmim][CI], [Bmim][PF6], [Bmim][AOc],[Amim][CI], [Emim][CI], [Dmim][CI]) was investigated and the maximum activity was observed in [Bmim][CI]. The hydrolytic activities in [Bmim][CI] was determined about 2-fold higher than the activities in buffer medium (100 mM, pH 7 phosphate buffer). After 12 reuses, the residual activity of combi CLEA (GA+GI) was about 23% of its initial activity. Combi CLEA (GA+GI) was protected 78% and 61% of its original activity at 5 ˚C and 25 ˚C respectively for four weeks.