Abstract: Enzyme-containing cells are immobilized on a water-insoluble support with a polymer represented by the following general formula (I): ##STR1## wherein Y is a direct bond or a divalent group represented by the following formula (II) ##STR2## R.sub.1 and R.sub.2 are each independently hydrogen atoms or organic residues, X.sup.- represents an anion, and n is an integer of 100 to 5000. The support may be in granular form such as granules of ion exchange resins or inorganic carriers, or in sheet form such as ion exchange films or alumina or silica sheets. Immobilization may be carried out by mixing cells with water and a quaternary salt of polyallylamine as the polymer, and sprinkling the resultant mixture onto the solid support and drying. L-aspartic acid or fumaric acid can be produced by contacting fumaric acid and ammonia, or ammonium fumarate, or maleic acid and ammonia, or ammonium maleate, with immobilized cells containing aspartase or maleate isomerase.

Abstract: A novel enzymatic, non-batch process for converting maleic acid to fumaric acid and/or producing L-aspartic acid, wherein dissolved oxygen concentration in the reaction medium in the reaction column or vessel is brought to 1 ppm (parts per million) or less with a deoxygenation agent and/or an inert gas, is provided.

Abstract: A process for production of L-aspartic acid comprising the steps of (1) contacting (A) an enzyme-containing material having maleate isomerase activity and aspartase activity, or (B) an enzyme-containing product having maleate isomerase activity and an enzyme-containing material having aspartase activity, with a substrate solution containing maleic acid and ammonia, and/or ammonium maleate to form L-aspartic acid, and (2) recovering L-aspartic acid from the reaction solution, characterized by adding maleic anhydride and/or maleic acid to the reaction solution to crystallize L-aspartic acid, and (3) recycling the mother liquors as the substrate solution by addition of ammonia.

Abstract: A radiation sensitizer of the present invention contains a particular nitrotriazole compound as an active ingredient and accelerates inactivation of intractable hypoxic cells in a malignant tumor by irradiation.