Toyo Soda Manufacturing Co., Ltd.

Tosoh Corporation

Holland Sweetener Company, V.o.f.

Ajinomoto Co., Ltd.

Sagami Chemical Research Center

Tsuneo Harada

Kiyotaka Oyama

Shigeaki Irino

Akira Tokuda

Hidetoshi Wakamatsu

Yukio Kunisawa

Masao Nakamura

Yasuhiro Kurauchi

Hisao Takemoto

Tatsuo Igarashi

Wilhelmus J Van Den Tweel

Johanna C Smeets

Hiyotaka Oyama

Ken-ichi Fukuda

Hiroshi Shimizu

Hideotoshi Wakamatsu

Shuya Takasuga

Shou Kawabe

Michihiro Akazawa

Tomiyoshi Fujiwara

To provide a hydrogenation catalyst which does not contain chromium oxide, unlike conventional copper/chromium oxide catalysts, and therefore does not cause any environmental contamination or health hazard, and which shows an activity, selectivity and durability at equivalent or higher levels to or than those of conventional copper/chromium oxide catalysts. A hydrogenation catalyst which comprises, as the main components, (1) copper and (2) at least one member selected from the group consisting of silicon oxide, calcium oxide and calcium silicate, wherein the content of the copper is from 20 to 60 wt % based on the entire amount of the hydrogenation catalyst, and in the calcium silicate, the molar ratio of calcium oxide (CaO) to silicon oxide (SiO) is less than 1.

Hydrogenation catalyst, process for its production and its use

A method for making a stabilized neutral metalloprotease enzyme composition is described in which a neutral metalloprotease and an aqueous solution are combined to obtain a solution or slurry thereof, whereby the stabilized neutral metalloprotease enzyme composition is obtained. The aqueous solution contains an N-protected amino acid, or an N-protected amino acid is added thereto. The invention also provides a stabilized neutral metalloprotease composition, and a method of transporting the stabilized neutral metalloprotease composition.

Stabilized neutral metalloprotease composition, a method of making the

The invention relates to a process for the preparation of N-protected-L-aspartyl-L-phenylalanine methyl ester by enzymatic coupling of an N-protected-L-aspartic acid and L- or DL-phenylalanine methyl ester in an aqueous solution with formation of a precipitate using a thermolysin-like protease enzyme, wherein a water-immiscible organic solvent is added to and blended with the reaction system during the formation of the precipitate in the course of the coupling reaction, which organic solvent has a relatively high affinity for the precipitate. The process is particularly suitable as a continuous process. The method results in lower enzyme deactivation during and after the enzymatic coupling reaction and in larger and thicker precipitated crystals.

Enzymatic coupling reaction of N-protected-L-aspartic acid and

A method for crystallizing .alpha.-L-aspartyl-L-phenylalanine methyl ester from a hot aqueous solution containing .alpha.-L-aspartyl-L-phenylalanine methyl ester by cooling is disclosed, which comprises (i) continuously supplying a hot aqueous solution of .alpha.-L-aspartyl-L-phenylalanine methyl ester having a concentration such that the content of L-aspartyl-L-aspartyl-L-phenylalanine methyl esters is less than 0.6% by weight based on the weight of .alpha.-L-aspartyl-L-phenylalanine methyl ester in said solution, or if the content of L-aspartyl-L-aspartyl-L-phenylalanine methyl esters is 0.6% by weight or more based on the weight of .alpha.-L-aspartyl-L-phenylalanine methyl ester in said solution, to a crystallization vessel the temperature of which is lowered to that corresponding to the solubility of .alpha.-L-aspartyl-L-phenylalanine methyl ester or less, and (ii) continuously discharging the formed slurry from the crystallization vessel.

Method for crystallizing .alpha.-L-aspartyl-L-phenylalanine methyl ester

A method for purifying a dipeptide ester by electrolysis in an electrolytic cell comprising an anode compartment, a cathode compartment and a central compartment partitioned by anion exchange membranes, which comprises supplying an aqueous dipeptide ester solution containing an inorganic acid to the central compartment defined by said anion exchange membranes, an aqueous solution containing a basic substance or an aqueous electrolyte solution containing a basic substance to the cathode compartment and an aqueous electrolyte solution to the anode compartment, supplying hydroxyl ions from the cathode compartment to the central compartment through the anion exchange membrane to neutralize the aqueous dipeptide ester solution containing the inorganic acid and removing anions of the inorganic acid in the aqueous dipeptide ester solution from the central compartment to the anode compartment through the anion exchange membrane.

Method for purifying a dipeptide ester

A process for producing dry .alpha.-L-aspartyl-L-phenylalanine methyl ester, which comprises drying wet crystals of .alpha.-L-aspartyl-L-phenylalanine methyl ester by means of an air having an absolute humidity of at least 0.015 kg/kg or at most 0.01 kg/kg.

Process for producing dry .alpha.-L-aspartyl-L-phenylalanine methyl ester

A process for producing stable .alpha.-L-aspartyl-L-phenylalanine methyl ester, which comprises heat-treating crystals of .alpha.-L-aspartyl-L-phenylalanine methyl ester having a water content of from 5 to 15% by weight based on wet crystals, at a temperature of higher than 50.degree. C. and lower than 80.degree. for at least 30 minutes.

Process for producing stable .alpha.-L-aspartyl-L-phenylalanine methyl

A method for purifying a dipeptide ester by electrolysis in an electrolytic cell comprising an anode compartment, a cathode compartment and a central compartment partitioned by ion exchange membranes, which comprises supplying an aqueous dipeptide ester solution containing organic acids to the central compartment defined by anion and cation exchange membranes or by anion exchange membranes and an aqueous electrolyte solution to the cathode and anode compartments, and electrically removing the organic acids from the central compartment to the anode compartment through the anion exchange membrane.

A process for producing dry .alpha.-L-aspartyl-L-phenylalanine methyl ester having an improved solubility by drying wet crystals of .alpha.-L-aspartyl-L-phenylalanine methyl ester, characterized in that the wet crystals of .alpha.-L-aspartyl-L-phenylalanine methyl ester are granulated so that the specific surface area during the drying operation is at least 4 m.sup.2 /g, followed by drying.

Process for producing alpha-L-aspartyl-L-phenylalanine methyl ester

A process for producing dry .alpha.-L-aspartyl-L-phenylalanine methyl ester having an improved solubility from wet crystals of .alpha.-L-aspartyl-L-phenylalanine methyl ester having a water content of at least 20% by weight, which comprises drying the wet crystals at a temperature of higher than 50.degree. C. to obtain moist crystals having a water content of less than 20 and more than 15% by weight, then drying the moist crystals at a temperature of not higher than 50.degree. C. to obtain semi-dry crystals having a water content of less than 5% by weight, and further drying the semi-dry crystals at a temperature of higher than 50.degree. C. to obtain dry crystals of .alpha.-L-aspartyl-L-phenylalanine methyl ester.

Process for producing alpha-aspartyl-l-phenylalanine methyl ester having

A method for racemizing an optically active amino acid, which comprises heating the optically active amino acid in an aqueous solution under an alkaline condition in the presence of an alkali metal salt.

Method for racemizing an optically active amino acid

A process for producing an addition compound of N-benzyloxycarbonyl-.alpha.-L-aspartyl-L-phenylalanine methyl ester and phenylalanine methyl ester. Benzyloxycarbonylation of the amino group of L-aspartic acid by benzyloxycarbonylchloride in the presence of a base and esterification of phenylalanine containing its L-body by methanol in the presence of an acid are carried out and both the reaction solutions are admixed after residual methanol is removed from the esterification reaction solution. A proteolytic enzyme is added to the resulting mixture solution after it is adjusted to have a pH, value, at which no substantial deactivation of the enzyme occurs. The reaction of N-benzyloxycarbonyl-L-aspartic acid and phenylalanine methyl ester is carried out in the solution at a pH, at which the proteolytic enzyme exerts the enzymatic activity to deposit the addition compound which is then recovered.

Process for producing an addition compound of a dipeptide ester and an

.alpha.-L-aspartylphenylalanine lower alkyl esters are prepared by a process wherein L-aspartic acid and a lower alkyl ester of L-phenylalanine are contacted with a culture or treated culture product of a microorganism belonging to the genus Pseudomonas, Alcaligenes, Torulopsis, Rhodotorula or Sporobolomyces and being capable of producing a .alpha.-L-aspartyl-L-phenylalanine lower alkyl ester from L-aspartic acid and a lower alkyl ester of L-phenylalanine.

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Shinnanyo, Japan

Tsuneo Harada