Abstract: A method for efficient production of an S-hydroxynitrile lyase by gene recombination using Escherichia coli is provided. A gene is formed by altering a codon in an S-hydroxyniitrylase gene originating in cassava (Manihot esculenta Crantz) without changing the amino acid sequence thereof till the frequency of codon usage wholly with an amino acid in Escherichia coli reaches a level of not less than 5%. According to the method for the production of an S-hydroxynitrile lyase by the use of the gene, the S-hydroxynitrile lyase can be produced in a large amount with an unusually high yield.

Abstract: A method for efficient production of an S-hydroxynitrile lyase by gene recombination using Escherichia coli is provided. A gene is formed by altering a codon in an S-hydroxyniitrylase gene originating in cassava (Manihot esculenta Crantz) without changing the amino acid sequence thereof till the frequency of codon usage wholly with an amino acid in Escherichia coli reaches a level of not less than 5%. According to the method for the production of an S-hydroxynitrile lyase by the use of the gene, the S-hydroxynitrile lyase can be produced in a large amount with an unusually high yield.

Abstract: This invention relates to a method for producing L-aspartic acid comprising treating an ammonium fumarate solution with aspartase to generate an ammonium L-aspartate solution; adding fumaric acid to the solution; and then crystallizing L-aspartic acid from the solution, wherein fumaric acid is added to the ammonium L-aspartate solution after the solution has been heated to 50 to 130° C. in an amount 0.4 to 0.8 times the total amount of fumarate and the L-aspartate contained therein in terms of mole, and the resultant mixture is once turned into a homogeneous solution by applying thereto a shearing force, and then L-aspartic acid is deposited therefrom, or wherein the solution is cooled at a rate of 0.1-5° C./min from the temperature at which fumaric acid is added thereto to the temperature at which crystallized L-aspartic acid is separated therefrom, to thereby deposit L-aspartic acid.

Abstract: A process for producing a polysuccinimide (co)polymer derivative which permits the reaction of a polysuccinimide (co)polymer with a Lewis base in a wide temperature range (90° to 300° C.) without using a pH-adjusting agent is provided. The process for producing a polysuccinimide (co)polymer derivative of this invention comprises reacting a polysuccinimide (co)polymer with a Lewis base by heating in the presence of a solvent having a low boiling point and high relative permittivity.

Abstract: A method capable of molding by a simple procedure such a polymer as a polysuccinimide based (co)polymer or a protein whose glass transition temperature is very close to the decomposition temperature is provided. The method for the molding of a polymer contemplated by this invention comprises heating and melting a polymer whose glass transition temperature is very close to the decomposition temperature in the presence of a solvent having a low boiling point and a high dielectric constant ratio and then molding the resultant molten product.

Abstract: A polyaspartic acid is obtained from an amino acid having aspartic acid as an essential component thereof without entailing formation of a bulk substance. A method for the production of polyaspartic acid is described which includes heating an amino acid having aspartic acid as an essential component thereof in the presence of water. A novel polyaspartic acid obtained by this method of production is described.

Abstract: A succinimide polymer is produced by thermally polymerizing an ammonium salt of aspartic acid in the presence of an acid catalyst such as a boric acid catalyst. Another amino acid may be added for copolymerizing with the ammonium salt of aspartic acid. Ammonia liberated during the production of a succinimide polymer can be collected in a fumaric acid suspension, an acidic fumaric acid solution, a maleic acid solution or an acidic maleic acid solution, and the resultant liquid reacted with an enzyme which may be immobilized to produce L-aspartic acid. An aspartic acid polymer is produced by hydrolyzing the succinimide polymer with a basic substance.

Abstract: This invention relates to a method for producing L-aspartic acid, comprising the steps of: immobilizing microbial cells containing aspartase to produce an immobilized aspartase; feeding an ammonium fumarate solution into a reactor filled with the immobilized aspartase; and recovering the produced L-aspartic acid from the reaction mixture, wherein the immobilized aspartase has an activity of 250 U or more, and wherein the ammonium fumarate solution is fed into the reactor at the feed rate LHSV of 2 to 35.

Abstract: A process for producing crystalline L-aspartic acid is disclosed essentially consisting of the steps of preparing a mix solution containing fumaric acid, ammonia and an alkaline metal hydroxide, reacting the mix solution with aspartase to give a reaction solution containing L-aspartate and crystallizing L-aspartic acid out of the reaction solution, wherein a further amount of ammonia is added to the reaction solution containing L-aspartate and subsequently fumaric acid is added thereto to crystallize L-aspartic acid. The process can provide crystalline L-aspartic acid of high purity in a good workability without the need of any complicated steps.

Abstract: The present invention provides a gene coding for maleate isomerase excellent in stability, a recombinant vector having the gene, and a transformant transformed with the recombinant vector. According to the present invention, maleate isomerase excellent in stability can be produced efficiently in a large amount.

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.