Background: Transglutaminase (TGase) catalyzes post-translational modification of proteins by γ-glutamyl-ϵ-lysine chain links, covalent conjugation of polyamines, and deamidation. Zea mays TGase (TGZ) is a plant TGase with potential application prospects in the food industry. In this study, two promoter types, PFLD1 and PTEF1 , were compared to improve the expression of TGZ, and the cross-linking effect of recombinant TGZ on the properties of acid-induced milk protein concentrate (MPC) gel was assessed.
Results: A higher expression of TGZ was obtained under the induction of PFLD1 with a production of 635 U L-1 . After purification using chromatography, TGZ activity was 0.4 U mg-1 . The results indicated that TGZ treatment has effectively improved the textural properties of MPC gel at strength level and water-holding capacity. Optimal texture of MPC gel was achieved after TGZ treatment using 2 U g-1 TGZ for 2 h at 35 °C and pH 7.
Conclusion: Comparative analysis of the promoters has greatly contributed to the production of TGZ in the industrial field. Furthermore, the modification of MPC gel texture by TGZ indicated that this recombinant enzyme has a practical value in dairy product, especially in yoghurt industry. © 2019 Society of Chemical Industry.
Keywords: Pichia pastoris; Zea mays transglutaminase; cross-linking effect; milk protein concentrate; promoter.
© 2019 Society of Chemical Industry.