Xu Shaohua, Ma Kexuan, Chen Zixiang, Zhao Jian, Song Xin, Qin Yuqi
National Glycoengineering Research Center, Shandong University, Qingdao 266237, China.
State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China.
Int J Mol Sci. 2025 Jul 17;26(14):6849. doi: 10.3390/ijms26146849.
Thermostable cellulases and xylanases have broad acceptance in food, feed, paper and pulp, and bioconversion of lignocellulosics. Thermophilic fungi serve as an excellent source of thermostable enzymes. This study characterized four endo-β-1,4-glucanases (two glycoside hydrolase (GH) family 5 and two GH7 members) and four endo-β-1,4-xylanases (two GH10 and two GH11 members) from thermophilic fungus , along with one GH10 endo-β-1,4-xylanase each from thermophilic fungus and mesophilic fungus . Comparative analysis was conducted against three previously reported GH10 endoxylanases: two thermostable enzymes from the thermophilic fungus and thermophilic bacterium , and one mesophilic enzyme from model fungus . The GH10 xylanase TtXyn10C (Thite_2118148; UniProt G2R8T7) from demonstrated high thermostability and activity, with an optimal temperature of 80-85 °C. It retained over 60% of its activity after 2 h at 70 °C, maintained approximately 30% activity after 15 min at 80 °C, and showed nearly complete stability following 1 min of exposure to 95 °C. TtXyn10C exhibited specific activity toward beechwood xylan (1130 ± 15 U/mg) that exceeded xylanases from and while being comparable to xylanase activity. Furthermore, TtXyn10C maintained stability across a pH range of 3-9 and resisted trypsin digestion, indicating its broad applicability. The study expands understanding of enzymes from thermophilic fungi. The discovery of the TtXyn10C offers a new model for investigating the high activity-stability trade-off and structure-activity relationships critical for industrial enzymes.
耐热纤维素酶和木聚糖酶在食品、饲料、造纸和木质纤维素生物转化领域得到广泛应用。嗜热真菌是耐热酶的优良来源。本研究对来自嗜热真菌的四种内切-β-1,4-葡聚糖酶（两种糖苷水解酶（GH）家族5成员和两种GH7成员）和四种内切-β-1,4-木聚糖酶（两种GH10成员和两种GH11成员）进行了表征，同时还对来自嗜热真菌和中温真菌的各一种GH10内切-β-1,4-木聚糖酶进行了研究。针对之前报道的三种GH10内切木聚糖酶进行了比较分析：两种来自嗜热真菌和嗜热细菌的耐热酶，以及一种来自模式真菌的中温酶。来自的GH10木聚糖酶TtXyn10C（Thite_2118148；UniProt G2R8T7）表现出高耐热性和活性，最适温度为80 - 85°C。在70°C下2小时后仍保留超过60%的活性，在80°C下15分钟后保持约30%的活性，在95°C下暴露1分钟后几乎完全稳定。TtXyn10C对山毛榉木聚糖表现出比来自和的木聚糖酶更高的比活性（1130±15 U/mg），与木聚糖酶活性相当。此外，TtXyn10C在pH 3 - 9范围内保持稳定并抵抗胰蛋白酶消化，表明其具有广泛的适用性。该研究扩展了对嗜热真菌酶的认识。TtXyn10C的发现为研究工业酶关键的高活性 - 稳定性权衡和结构 - 活性关系提供了新的模型。
