Explore the characteristics of L-fucose isomerase from different sources
學生姓名:
林于彤
指導教授:
方翠筠
學期:
112上
摘 要:
L-fucose and L-fuculose are both rare sugars with excellent potential applications in the fields of medicine and agriculture. Preparation methods include chemical, physical, and enzymatic approaches, with enzymatic methods being safer, gentler, less susceptible to contamination, and free from byproducts. Therefore, the purpose of this study is to explore the preparation of L-fucose or L-fuculose using L-fucose isomerases from different sources and analyze their characteristics. Results indicate that the recombinant L-fucose isomerase, Capo-LfIase, from Caldanaerobius polysaccharolyticus, exhibits optimal activity at 55°C and pH 6.5, showcasing high thermal stability with a melting temperature (Tm) of 80.3°C. The presence of Mn2+ and Co2+ enhances Capo-LfIase's catalytic activity. Ca2+, Fe2+, Ni2+, Mg2+, Cu2+, Ba2+ , and Zn2+ decreased the activity of Capo-LfIase. Capo-LfIase demonstrates higher substrate specificity for L-fucose, with Km, kcat and catalytic efficiency (kcat / Km) values of 94.2 mM, 23854 min−1, and 253.3 min−1 mM−1, respectively. The conversion rate of 80 g L−1 L-fucose to L-fuculose is 28.2%, showing significant potential for industrial applications. On the other hand, the recombinant L-fucose isomerase, TtFucl, from Thermanaeromonas toyohensis, exhibits optimal activity at 70°C and alkaline pH. The addition of Mn2+ and Mg2+ enhances its activity, with Mn2+ further improving TtFucl's thermal stability and catalytic activity. TtFucl demonstrates a specific activity of 199.8 U/mg at 70°C, with Km (Michaelis constant) and kcat (turnover number of substrate) values of 33.4 mM and 901.7 s−1 , respectively. It displays better substrate specificity for L-fuculose, suggesting its potential application in the industrial production of L fucose.
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