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。