Abstract: Lipase has been successfully immobilized by crosslinking with glutaldehyde onto a low-cost magnetic microspheresmade of starch and magnetite powder. The result shows that the mass activity, protein binding, specific activity、 activity retention、optimum temperature and optimum pH of the magnetic immobilized lipase were respectively 4897.15U/g、50.59mg/g、98.58U/mg、72.73%、45℃ and 8. The Ca2+、Na+ and Mg2+ enhanced the activities of immobilized lipase and free lipase,and the action was in the order: Ca2+>Mg2+>Na+. They were inhibited by Cu2+ and Fe2+, particularly by Cu2+. As comparedwith free lipase, the operational , thermal and acid-basc stabilities of immobilized lipase were increased appreciably .After used6 times in the degradation of fat, immobilized lipase retained 67.9 percent of its initial activity. After 34 days at 4℃ in PBS (pH8)and hexane, their remaining activities were respectively 78.3% and 98.8%.

Key words: magnetic starchy microspheres, lipase, immobilized enzyme