Immobilization of Saccharomyces cerevisia invertase on carboxylated multi walled carbon nanotubes

The invertase, an industrial enzyme, is a glycoprotein that catalyzes the hydrolysis of sucrose and is used in the production of invert sugar in the food industry. Invert sugar, consisting of 1: 1 mixture of glucose and fructose, is more sweet and soluble than sucrose and is an important component in the food industry. It is especially used for the purpose inhibite the crystallization of sugar in high viscosity solutions of sugar based products. In this study, the immobilization of Saccharomyces cerevisiae invertase was carried out by adsorption method on the carboxylated multi-walled carbon nanotube, which is a commercial immobilization matrix. By optimizing the immobilization conditions, 100% immobilization efficiency and 177.69% efficiency were obtained. The optimum pH (4.5) and optimum temperature (55 ° C) of the enzyme did not change after immobilization. In addition, kinetic constants for free and immobilized enzyme were determined using Linereaver-Burk graph. When sucrose was used as the substrate, the Km values for the free and immobilized enzyme were calculated as 215.5 mM and 140.9 mM, respectively, while the Vmax values were 0.0339 µmol / mg.min. and 0.0481 µmol / mg.min. The immobilized enzyme did not lose its initial activity during repeated use and also during twenty days of storage. When the hydrolysis of sucrose was monitored for 6 hours using the immobilized enzyme at optimum conditions (pH 4.5 and 55 ° C) with an orbital shaker and heated incubator at a shaking rate of 150 rpm, the hydrolysis was completed in 4 hours. In conclusion, it can be said that Saccharomyces cerevisiae invertase immobilized on the carboxylated multilevel carbon nanotube obtained in this thesis study can be used in the industrial production of invert sugar.