Expression of Zea mays transglutaminase in Pichia pastoris under different promoters and its impact on properties of acidified milk protein concentration (MPC) gel.

BACKGROUND: Transglutaminase catalyze posttranslational modification of proteins by γ-glutamyl-ε-lysine chain links, covalent conjugation of polyamines and deamidation. Zea mays transglutaminase (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 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: The comparative analysis in the promoters has greatly contributed the production of TGZ in the industrial field. Furthermore, the modification of MPC gel texture by TGZ indicated that this recombinant enzyme had a practical value in dairy product especially in yoghurt industry. This article is protected by copyright. All rights reserved.