Novel immobilization process of a thermophilic catalase: efficient purification by heat treatment and subsequent immobilization at high temperature

The main goal of the present work is to investigate a novel process of purification and immobilization of a thermophilic catalase at high temperatures. The catalase, originated from Bacillus sp., was overexpressed in a recombinant Escherichia coli BL21(DE3)/pET28-CATHis and efficiently purified by heat treatment, achieving a threefold purification. The purified catalase was then immobilized onto an epoxy support at different temperatures (25, 40, and 55 degrees C). The immobilizate obtained at higher temperatures reached its maximum activity in a shorter time than that obtained at lower temperatures. Furthermore, immobilization at higher temperatures required a lower ionic strength than immobilization at lower temperatures. The characteristics of immobilized enzymes prepared at different temperatures were investigated. The high-temperature immobilizate (55 degrees C) showed the highest thermal stability, followed by the 40 degrees C immobilizate. And the high-temperature immobilizate (55 degrees C) had slightly higher operational stability than the 25 degrees C immobilizate. All of the immobilized catalase preparations showed higher stability than the free enzyme at alkaline pH 10.0, while the alkali resistance of the 25 degrees C immobilizate was slightly better than that of the 40 and 55 degrees C immobilizates.