Nitto Electric Industrial Co., Ltd.

Kazuo Nakao

Takeshi Okada

Ken Hibino

Yuko Sahashi

An enzyme immobilized membrane comprising an anisotropic ultrafiltration membrane having a porous layer and a dense layer, and an enzyme immobilized therein is disclosed. The porous layer of the ultrafiltration membrane retains a water-soluble polymer having at least two functional groups in the crosslinked state, and the enzyme is covalently bonded to the membrane through the functional groups of the polymer. Preferably, the membrane is prepared from polysulfone. The enzyme immobilized membrane is produced by a process which comprises impregnating a solution of the water-soluble polymer into the porous layer of the ultrafiltration membrane under a pressure of 0.1 to 1.0 kg/cm.sup.2, washing the porous layer, passing a solution of a crosslinking agent through the porous layer under a pressure within the same pressure range as above to crosslink the water-soluble polymer, removing the non-crosslinked water-soluble polymer by back washing from the dense layer of the membrane, and then passing a solution of the enzyme under a pressure within the same pressure range as above through the porous layer, whereby the enzyme is covalently bonded to the membrane through the functional groups of the polymer.

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Osaka, Japan

Kazuo Nakao