α-Amylase Immobilized Composite Cryogels: Some Studies on Kinetic and Adsorption Factors

Stability of enzymes is a significant factor for their industrial feasibility. α-Amylase is an important enzyme for some industries, i.e., textile, food, paper, and pharmaceutics. Pumice particles (PPa) are non-toxic, natural, and low-cost alternative adsorbents with high adsorption capacity. In this study, Cu2+ ions were attached to pumice particles (Cu2+-APPa). Then, Cu2+-APPa embedded composite cryogel was synthesized (Cu2+-APPaC) via polymerization of gel-forming agents at minus temperatures. Characterization studies of the Cu2+-APPaC cryogel column were performed by X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), and Brunauer, Emmett, Teller (BET) method. The experiments were carried out in a continuous column system. α-Amylase was adsorbed onto Cu2+-APPaC cryogel with maximum amount of 858.7 mg/g particles at pH 4.0. Effects of pH and temperature on the activity profiles of the free and the immobilized α-amylase were investigated, and results indicate that immobilization did not alter the optimum pH and temperature values. kcat value of the immobilized α-amylase is higher than that of the free α-amylase while KM value increases by immobilization. Storage and operational stabilities of the free and the immobilized α-amylase were determined for 35 days and for 20 runs, respectively.