A preparation of invertase immobilized on polyamide through glutaraldehyde has been obtained in a medium with a high concentration of substrate (60% sucrose). The optimum concentrations of glutaraldehyde and enzyme have been selected and the substrate dependences of the native and immobilized enzymes have been determined. It has been shown that the covalent addition of invertase to polyamide carried out in the presence of 60% sucrose leads to the most stable immobilized preparation.Invertase is one of the most important enzymes used in industry. For effective use, it must be immobilized. Reports are found in the literature of the immobilization of invertase on aminopolystyrene through glutaraldehyde [1] and on siliceous sorbents modified with an organosilane and activated by glutaraldehyde [2]. These immobilized preparations are not distinguished by high activity, as is confirmed in the literature. It is assumed that the active center of invertase contains an imidazole group. According to this, the enzyme is bound to the glutaraldehyde-modified support through the functional groups of its catalytic center [3]. We have therefore conducted immobilization in the presence of a substrate blocking the catalytic center, which gave a considerable increase in enzyme activity (485 units/h).The immobilization of invertase was carried out on polyamide through the amino groups of the invertase and the amino groups of activated polyamide in a substrate -sucrose. Glutaraldehyde was used as the bifunctional agent.The addition reaction was carried out at room temperature by the principle of Schiff's base formation. The number of enzyme molecules attached to the support was found by determining the loss of protein from the initial solution in the binding process and taking into account the quantity of enzyme desorbed from the support by washing [4]. The activity of the enzyme was determined for glucose [5]. It was established that on immobilization in the absence of a substrate, the specific activity amounted to 122 units/h at a relative concentration of the binding agent of 0.1%.A determination of the dependence of +the enzyme activity of the immobilized preparation on the initial weight ratio of enzyme to support showed that the maximum specific activity was obtained with the use of 7 mg of protein per 1 g of support. Binding of the enzyme was carried out at pH 7.5-9.0, in steps of 0.5 unit. The greatest activity of the enzyme was noted in the region with an immobilization Ph of 8.5. Figure 1 shows the dependence of the initial rate of hydrolysis of sucrose on its concentration. The maximum activity of the enzyme was observed on the addition of a 0.75 M solution of sucrose to the medium, while for the immobilized enzyme it was observed for a 1.0 M solution. Both a decrease and an increase in the amount of sucrose in the solution led to a fall in the initial rate of the reaction. The decrease in the initial rate at low concentrations of sucrose of hydrolysis is explained by the law of mass action. The fall in the initial rate of ...
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