Covalent Immobilization of Invertase on Methacrylic Acid-Based Nanogel & its Specialty Application in Biomedical Field

Abstract

Nano-bioreactors are becoming increasingly important in the chemical transformations. The nano-size of the enzyme support provides large surface area for the covalent binding between its functional sites and those of the biocatalyst. In the present study, invertase extracted from Saccharomyces cerevisiae was immobilized on the functional copolymeric nanogels by the covalent binding via azide method. The immobilized enzymes were tested for sucrose hydrolysis activity by standard DNS method spectrophotometrically at λmax = 540 nm. The immobilized-invertase was tested for stability after 30 days of its storage and reused for 12 continuous cycles. Covalent binding results in improving the spectrum of enzyme activity over a larger range of temperature and pH as high activity was observed even at 65 °C and a wide range of pH, hence, covalent immobilization on the nanogels stabilized invertase over a wide range of operating conditions than its free form. The nanogels with and without the immobilized invertase was characterized by the nitrogen analysis, FTIR, SEM, XRD, TEM and elemental analysis (% nitrogen estimation) which provide the evidence of covalent binding of invertase on the functional surface of the nanoparticles. The kinetics of the sucrose hydrolysis by the invertase-immobilized nanogels was determined by the Lineweaver-Burke plot or Eddie-Hofstee model. The value of Vmax (0.249 unit/mg), Km (14.89 mol/L) and Ea (2.697 kj/mol) were calculated for the immobilized invertase, and these are significantly different than those obtained for the free invertase.