Method for cross-linking proteins
Publication Date: 2002-Dec-04
The IP.com Prior Art Database
The present invention relates to a method for cross-linking proteins by means of a peroxidase and a H2O2 generating carbohydrate oxidase. The invention further relates to the use of a peroxidase and a H2O2 generating carbohydrate oxidase for cross-linking proteins and to products including cross-linked proteins produced by the above method.
METHOD FOR CROSS-LINKING PROTEINS
The present invention relates to a method for cross-linking proteins for providing modified proteins having improved functionality.
BACKGROUND OF THE INVENTION
Increasing interest is directed towards modifying proteins to enhance functionality and thereby add value to the proteins. Protein functionality can be changed by chemical, physical and enzymatic methods. The advantage of using enzymatic modification instead of chemical modification is the higher specificity of enzymatic reactions, thus minimizing the risk of formation of possible toxic products.
Enzymatic cross-linking has been investigated in some detail using the enzyme transglutaminase (EC 18.104.22.168). Transglutaminase catalyzes acyl transfer reactions using peptide-bound glutamine residues as donors and various primary amines, for example, peptide-bound lysine, as acyl acceptors (Folk and Finlayson, 1977). The enzyme is thus able to form intra- or intermolecular έ-(y-glutamyl)-lysine cross-links. Many food proteins are good substrates for transglutaminase-catalyzed cross-linking, and among the milk proteins the caseins are especially excellent substrates for transglutaminase (Ikura et al., 1980; Sakamoto et al., 1994; Traoré and Meunier, 1991, 1992). It is possible to polymerise the other main part of the milk proteins, the whey proteins quite extensively using transglutaminase (Færgemand et al., 1997), but only when the whey proteins are partly unfolded. It is therefore of interest to investigate other possibilities for cross-linking native whey proteins.
Matheis and Whitaker (1987) have reviewed various enzymatic reactions that may possibly induce cross-linking in food proteins and proposed that besides the transglutaminase-catalyzed reaction, especially oxidative cross-linking, using various oxidoreductases, should be considered.
Consequently peroxidase mediated cross-linking may be an alternative to the use of transglutaminases in protein products, such as dairy products. However, the addition of hydrogen peroxide may not be acceptable in food applications and high concentrations of hydrogen peroxide is problematic in e.g. fermented products due to its inhibiting effect on bacterial growth.
In view of the above disadvantages there is a need for an improved method for cross-linking proteins.
An object of the present invention is to provide a method for preparing a source of protein to be used in food industry, the method being an improvement over presently known methods.
A further object of the present invention is to provide a source of protein to be used in food industry.
SUMMARY OF THE INVENTION
According to the invention it has been found that by the use of a combination of a peroxidase and a carbohydrate oxidase proteins may be cross-linked in a more efficient and advantageous way.
Thus, the present invention relates to a method for cross-linking proteins comprising adding to a protein a...