Ono Takuto, Takahashi Kazutoshi, Hirao Yoshinori, Mihara Yasuhiro, Abe Isao, Shirasawa Ayaka, Sugiki Masayuki
Research Institute for Bioscience Products & Fine Chemicals, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa-ken, 210-8681, Japan.
Sci Rep. 2025 Jul 1;15(1):21105. doi: 10.1038/s41598-025-07842-5.
Microbial transglutaminase (MTG) is an enzyme that catalyzes the cross-linking of glutamine and lysine residues in proteins. Because of its ability to modify proteins, MTG has various applications in the medical and food industries. Most studies have aimed to enhance the thermal stability of MTG by focusing only on point mutations. Introducing a disulfide (S-S) bond in the N-terminal region has been found to be effective, whereas S-S bonds in other regions were considered ineffective. Therefore, this study aimed to evaluate the impact of introducing an additional S-S bond on the thermal stability of an MTG mutant. We found that adding S-S bonds to regions other than the N-terminal, in conjunction with the N-terminal S-S bond, significantly enhanced thermal stability. This finding demonstrates the importance of reinforcing the weakest part of the protein first, followed by strengthening other regions for optimal thermal stability. The MTG variant with two S-S bonds retained its catalytic activity and substrate specificity towards protein substrates, making it a promising candidate for industrial applications. Thus, introducing S-S bonds could be an effective strategy to increase thermal stability of MTG and other industrial enzymes, thereby contributing to their potential industrial applications.
微生物转谷氨酰胺酶（MTG）是一种催化蛋白质中谷氨酰胺和赖氨酸残基交联的酶。由于其修饰蛋白质的能力，MTG在医学和食品工业中有多种应用。大多数研究仅聚焦于点突变来提高MTG的热稳定性。已发现在N端区域引入二硫键（S-S）是有效的，而其他区域的S-S键则被认为无效。因此，本研究旨在评估引入额外的S-S键对MTG突变体热稳定性的影响。我们发现，除了N端的S-S键外，在其他区域添加S-S键能显著增强热稳定性。这一发现表明，首先加强蛋白质最薄弱的部分，然后再强化其他区域以实现最佳热稳定性非常重要。具有两个S-S键的MTG变体保留了其对蛋白质底物的催化活性和底物特异性，使其成为工业应用的一个有前景的候选物。因此，引入S-S键可能是提高MTG和其他工业酶热稳定性的有效策略，从而有助于它们在工业上的潜在应用。
