Abstract：
Microbial transglutaminases (MTGs) are widely used in the food industry. In this study, the MTG gene of Streptomyces sp. TYQ1024 was cloned and expressed in a food-grade bacterial strain, Bacillus subtilis 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.
摘要：
微生物转谷氨酰胺酶(MTGs)广泛用于食品工业。在这项研究中,链霉菌的MTG基因。TYQ1024被克隆并在食品级细菌菌株中表达，枯草芽孢杆菌SCK6。密码子和信号肽（SPYncM）优化后的MTG的细胞外活性是预优化酶的20倍。纯化后,MTG的分子量为38kDa，比活性为63.75U/mg。重组MTG活性的最佳温度和pH分别为50°C和8.0。MTG活性在β-ME存在下增加1.42倍，在DTT存在下增加1.6倍。此外，18％的氯化钠仍然导致83％的酶活性，表现出良好的耐盐性。用MTG交联明胶将明胶的强度提高了1.67倍，并将热变性温度从61.8°C提高到75.8°C。MTG还显著增加了明胶的强度和热稳定性。这些特点证明了MTG的巨大商业潜力，例如在加盐蛋白质食品中的应用。
