Key Laboratory of Leather Chemistry and Engineering (Sichuan University), Ministry of Education, Chengdu 610065, P.R. China.
College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, P.R. China.
J Microbiol Biotechnol. 2020 Jul 28;30(7):1082-1091. doi: 10.4014/jmb.2002.02049.
Microbial transglutaminases (MTGs) are widely used in the food industry. In this study, the MTG gene of sp. TYQ1024 was cloned and expressed in a food-grade bacterial strain, SCK6. Extracellular activity of the MTG after codon and signal peptide (SP Ync M) optimization was 20 times that of the pre-optimized enzyme. After purification, the molecular weight of the MTG was 38 kDa and the specific activity was 63.75 U/mg. The optimal temperature and pH for the recombinant MTG activity were 50°C and 8.0, respectively. MTG activity increased 1.42- fold in the presence of β-ME and 1.6-fold in the presence of DTT. Moreover, 18% sodium chloride still resulted in 83% enzyme activity, which showed good salt tolerance. Cross-linking gelatin with the MTG increased the strength of gelatin 1.67 times and increased the thermal denaturation temperature from 61.8 to 75.8°C. The MTG also significantly increased the strength and thermal stability of gelatin. These characteristics demonstrated the huge commercial potential of MTG, such as for applications in salted protein foods.
微生物转谷氨酰胺酶（MTG）广泛应用于食品工业。本研究克隆并在食品级菌株 SCK6 中表达了 sp. TYQ1024 的 MTG 基因。经密码子和信号肽（SP Ync M）优化后，MTG 的胞外活性是预优化酶的 20 倍。经纯化后，MTG 的分子量为 38 kDa，比活为 63.75 U/mg。该重组 MTG 的最适温度和 pH 分别为 50°C 和 8.0。β-ME 和 DTT 的存在可使 MTG 活性分别增加 1.42 倍和 1.6 倍。此外，18%的氯化钠仍可使酶活保持 83%，表明其具有良好的耐盐性。MTG 使明胶交联，使明胶的强度增加 1.67 倍，热变性温度从 61.8°C 提高到 75.8°C。MTG 还显著提高了明胶的强度和热稳定性。这些特性表明 MTG 具有巨大的商业潜力，例如可应用于含盐蛋白食品。
