The present invention addresses the problem of providing a novel protein crosslinking method. In the present invention, a crosslinking reaction is accelerated by causing both an oxidoreductase such as a laccase and a protein deamidase such as a protein glutaminase to act on a substrate protein.

A technique of using a compositional innovation of a dry enzyme composition to improve the stability of a protein deamidase composition enables improvement of the stability of a dry protein deamidase composition by making both a protein deamidase and magnesium chloride coexist in a dry enzyme composition. The technique involves making adjustments so that the pH is at least 2 and less than 5 when the composition is dissolved in water at a concentration of 1 w/v %.

The present invention addresses the problem of promoting a deamidation reaction with a protein deamidation enzyme. The present invention aims to promote the deamidation reaction by reacting a protein deamidation enzyme with a protein in the presence of a salt or a polysaccharide. According to the present invention, the reaction efficiency can be improved. The present invention is especially useful for the deamidation of a vegetable protein such as a pea protein. A deamidated protein (especially a deamidated vegetable protein) produced by employing the present invention can be used in various foods or beverages.

The present disclosure discloses a method for modification of mung bean protein and preparation of simulated egg pulp based on the modified protein. A commercial mung bean protein isolate is used as a raw material in the present disclosure, then subjected to pH shift modification, ultrasonic treatment and protein-glutaminase treatment for compound modification to prepare a high-functionality modified mung bean protein isolate; and the modified mung bean protein isolate is used as a raw material, using high-speed emulsification and high-pressure homogenization are conducted to obtain a high-stability mung bean protein-based simulated egg pulp. In the present disclosure, the mung bean protein isolate prepared by compound modification has good solubility, emulsifying property and gelling property. The mung bean protein-based simulated egg pulp is in the form of a stable emulsion and has good fluidity and moderate gelling property, and uniformity and stability can still be maintained for a long time.

Aggregation in a nut milk is prevented by increasing dispersibility of the nut milk by treating the nut milk with a protein deamidase. When the protein deamidase-treated nut milk is added to a liquid beverage or a liquid food, aggregation in the protein deamidase-treated nut milk is prevented due to the increased dispersibility of the protein deamidase-treated nut milk.

A dispersibility of a vegetable milk under a high temperature condition is increased by treating the vegetable milk with a protein deamidase. When the protein deamindase-treated vegetable milk is added to a liquid beverage or a liquid food at a high temperature, an aggregation in the protein deamindase-treated vegetable milk is prevented.

The present invention addresses the problem of creating an effective means for preventing the coagulation of a plant milk under high temperature conditions. To solve this problem, a plant milk is treated with a protein deamidase to thereby prevent the coagulation of the plant milk in the case of adding to a hot liquid beverage, a hot liquid food, etc.

A novel technique for reducing the mis-cleavage of the TorA signal peptide, and thereby a method for efficient secretory production of a heterologous protein by a coryneform bacterium using a TorA signal peptide is provided. A coryneform bacterium having an ability of secretory production of a heterologous protein using a TorA signal peptide and has been modified so that the activity of a LepB protein is increased is cultured to produce the heterologous protein by secretory production.

Disclosed is a protein glutaminase having improved thermotolerance. A protein glutaminase comprising a polypeptide indicated in any among (1) to (3) has improved thermotolerance. (1) A polypeptide comprising a SEQ ID NO: 1 or 2 amino acid sequence; (2) a polypeptide wherein one or more amino acid residues are substituted, added, inserted or lost in the amino acid sequence indicated by SEQ ID NO: 1 or 2 and exhibiting the same thermotolerance as the amino acid sequence indicated by SEQ ID NO: 1 or 2: and (3) a polypeptide having at least 76% sequence identity with the amino acid sequence indicated by SEQ ID NO: 1 or 2 and having similar thermotolerance to a polypeptide comprising the amino acid sequence indicated by SEQ ID NO: 1 or 2.

The purpose of the present invention is to provide a technology that enables control for increasing or decreasing the heat coagulation gel strength of egg white protein, and that has little effect on taste. This heat coagulation gel strength regulating agent for egg white protein contains a protein deamidase and can control the increase or decrease of the heat coagulation gel strength of egg white protein.