Silica gels activated by BCl3 and aliphatic diamines as supports for glucoamylase immobilization

TkaGlucoamylase (E.C.3.2.1.3)is the most popular enzyme used for industrial purposes in the starch solubilization process.'This enzyme, immobilized on organic and inorganic matrices, has been used in research laboratories and in pilot plants on a half-industrialThe biotechnological use of immobilized enzymes requires cheap, easily prepared and chemically stable supports.Numerous methods developed to bind enzymes on many different supports have been reported and thoroughly discussed.""Some methods are based on the reaction between glutaraldehyde and the amino-groups carried by the matrix.The most common way of introducing free amino groups on the support having reactive hydroxyl groups is silanization involving y-aminopropyl-triethoxysilane.In the present communication, we report a new method of amino functionalization of the support for the covalent binding of glucoamylase.This method includes a two-step activation of silica supports with gaseous BC13 to form reactive B-Cl groups with aliphatic diamine, ethylene diamine, or hexamethylenediamine.The procedure of the activation is simple and it ensures the covalent binding of amino-groups with an alkyl-spacer arm, enzyme coupling to aminofunctionalized silica was successful with all the tested silica samples and ensured a good stability of enzyme activity. EXPERIMENTAL Materiats and Methods EnzymeGlucoamylase (E.C.3.2.1.3)was obtained from a filtrate of a submerged culture of Aspergillus niger.I' The activity * To whom all correspondence should be addressed.