Sulfuric Acid → Ethyl methioninate

Temperature

90 °C

In 2.5 liters of water containing 85 g of sodium carbonate and 26 g of sodium hydrogen carbonate, were dissolved 33 g of papain and 3.3 g of L cysteine as a papain activator. With stirring, 1 kg of a commercial soybean protein (manufactured and sold by Fuji Seiyu K.K. under trade name "Fujipro R") in limited amounts was added to the solution and thoroughly mixed and agitated. Separately, a suspension of 50 g of L-methionine in 320 ml of ethyl alcohol was gradually added to 35 ml of conc. sulfuric acid to completely dissolve the methionine. The solution was heated under reflux at 90° C. for 5 hours, obtaining a reaction solution of L-methionine ethyl ester in an yield of 92.3%. The reaction solution was diluted with ethyl alcohol to a volume of 500 ml. A 370-ml portion of the diluted reaction solution was added to the separately prepared protein system. After thorough mixing and agitation, the solution was kept at 37° C. for 24 hours to effect plastein reaction. The yield of L methionine incorporated in the thus produced protein-like material was 88.1% based on the amount of L-methionine ethyl ester added at the start of the reaction. The reaction solution was then diluted with water to a volume of 20 liters and adjusted to pH 6-7 with hydrochloric acid before it was subjected to repeated concentration operations for desalting and purification using a reverse osmosis membrane (tubular type, manufactured by Daicell Chemical K.K. under tradename DRS-10) under an operating pressure of 15 kg/cm2. The concentrate resulting from the reverse osmosis treatment was again diluted with water to a volume of 20 liters and adjusted to pH 3 with phosphoric acid. Then, 20 g of orientase (manufactured by Hankyu Kyoei Bussan K.K.) and 20 g of molsin (manufactured by Fujisawa Chemicals K.K.) were added to the solution, which was kept at 40° C. for 40 hours to effect hydrolysis. During the reaction, the solution was controlled to pH 3 with a 6N phosphoric acid. At the end of the reaction, the solution was heated to 90° C. for 10 minutes to deactivate the proteases. The solids were removed by filtration, and the filtrate was spray dried to yield 685 g of a dry powder, which was a low-molecular weight peptide mixture having L-methionine replenished in the form of an acid residue. The low-molecular weight peptide mixture was found to have an average molecular weight of 320. A sample of the powder was subjected to gel filtration using Cephadex G-10 to find that 87.3% of the sample had a molecular weight of 700 or lower. It was also found that the content of free amino acids was 9.8%. Table 1 shows the amino acid composition of the starting soybean protein and low-molecular weight peptide mixture produced therefrom.

1. addition1 kg of a commercial soybean protein (manufactured and sold by Fuji Seiyu K.K. under trade name "Fujipro R") in limited amounts was added to the solution
2. additionthoroughly mixed
3. stirringagitated
4. temperatureThe solution was heated

ORD record

ord-5c367469b7b541afa10a1c6fda7b6f8f

Source dataset

uspto-grants-1990_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04940662