In this research, His Mag Sepharose Ni magnetic beads were employed to simultaneously purify and immobilize histidine-tagged Bacillus licheniformis aldehyde dehydrogenase (His-BlALDH). The optimal conditions for the adsorption of His-BlALDH on the matrix were 24.6 U/mg adsorbent, incubation at 4 °C for 1 h and the addition of 500 mM NaCl into the crude cell-free extract, and the bound enzyme could be efficiently eluted by 20 mM phosphate buffer (pH 7.4) containing 500 mM NaCl and 500 mM imidazole. Free His-BlALDH was active in temperature range of 30 – 40 °C and had an optimum of 37 °C, while its thermal stability was improved as a result of immobilization. The immobilized enzyme was recycled six times without an obvious loss of the dehydrogenase activity. Up to 20 days of storage, the preserved activity of free and immobilized enzyme was found to be 2.1% and 78.2%, respectively. Collectively, this magnetic adsorbent may be useful for a novel purification-immobilization of His-BlALDH.
Aldehyde dehydrogenase, Bacillus licheniformis· His tag, Mag Sepharose Ni, Enzyme immobilization
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