Fuji Oil Company Limited

Masao Fujimaki

Michiko Watanabe

Soichi Arai

Yukio Hashimoto

Akira Kurooka

A modified protein composition which is produced by contacting a water-soluble protein, such as plant seed proteins, cow milk protein, animal meat proteins, fish meat proteins, egg proteins and microorganisms proteins, with a cysteine-enriched plastein in an amount of at least 1% by weight on the basis of the water-soluble protein in an aqueous medium, and if desired, heating the resultant under a mild condition (e.g. at a temperature of 40.degree. to 90.degree. C.), said cysteine-enriched plastein being produced by hydrolyzing a protein with an enzyme having an endopeptidase activity and subjecting the hydrolyzate to dehydration-condensation with a protease having an esterase activity in the presence of an activated cysteine (e.g. lower alkyl cysteinate, N-acetyl-L-cysteine or L-cysteinyl-L-cysteine).

Modified protein compositions and preparation thereof

Method for the preparation of a low-phenylalanine plastein comprising hydrolyzing stepwise a certain albumin or globulin protein with an endopeptidase having an affinity for the aromatic acid components, and an exopeptidase, subjecting the hydrolyzate thus-obtained to gel-filtration to divide it into two fractions, one being constituted with aromatic amino acids and the other being constituted with oligopeptides almost free from the aromatic amino acids, and then subjecting the latter fraction to usual plastein synthesis. Tyrosine and/or tryptophan may be added to the substrate at the plastein synthesis in order to incorporate them into the plastein molecules. The resultant plasteins may be purified through ultra-filtration in order to remove the remaining free amino acids and low-molecular peptides.

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Tokyo, Japan

Masao Fujimaki