Abstract.
Tyrosinase (EC 1.14.18.1), usually known as the enzyme responsible for the enzymatic browning of fruits and vegetables, has been demonstrated to induce cross-linking of the whey proteins α-lactalbumin and β-lactoglobulin. The maximum degree of polymerisation for 1.5 mg/ml protein has been achieved at a tyrosinase activity of about 330 U/ml in the presence of a 2 mM concentration of caffeic acid. The pH optimum for the cross-linking reaction was detected at pH 4–5 for α-lactalbumin and β-lactoglobulin, in contrast to pH 7 for lysozyme, a non-whey protein, indicating that for the whey proteins the initial enzymatic oxidation of the phenolic compound is not the rate limiting step for the reaction. In contrast to β-lactoglobulin and lysozyme, for α-lactalbumin a direct cross-linking even without addition of caffeic acid has been proved. In this manner α-lactalbumin polymers with a molecular weight larger than 300 kDa have been produced by increasing the reaction temperature up to 50 °C. The results of the present study represent a basis for the creation of new high molecular weight proteins. Due to a different reaction mechanism and different points of linkage, tyrosinase-induced protein cross-linking may be a promising alternative to the already established use of transglutaminase for food application.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Thalmann, C., Lötzbeyer, T. Enzymatic cross-linking of proteins with tyrosinase. Eur Food Res Technol 214, 276–281 (2002). https://doi.org/10.1007/s00217-001-0455-0
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/s00217-001-0455-0