Efficient degradation of fucoidan polysaccharide extracted from F. vesiculosus by using a novel GH107 family thermostable fucoidanase

Fucoidan exhibits diverse physiological activities and holds significant potential for applications in the food and pharmaceutical industries. Fucoidan oligosaccharides produced through the enzymatic degradation of fucoidan retain the beneficial properties of polysaccharides while demonstrating improved solubility, bioavailability, and bioactivity. Fucoidanases are essential in studying the structure of fucoidans and producing fucoidan oligosaccharides. However, there is limited research on the structural characterization of fucoidanases that specifically degrade fucoidan, which is essential for fully harnessing the biological activities of the resulting oligosaccharides. In this study, a novel fucoidanase, FcnA, was identified and heterologously expressed. This enzyme could specifically hydrolyze fucoidan from Fucus vesiculosus, and exhibited an activity of 399.364 U/mg and demonstrating optimal activity at 50 °C and pH 6.0. The K_m value of FcnA was 1.0 mg/mL and the V_max value was 416.67 U/mg. Additionally, FcnA exhibits mesophilic temperature tolerance, retaining over 80 % of its relative activity after incubation for 1 h at temperatures of 50 °C. The results of HPLC and ESI-MS revealed that FcnA could degrade fucoidan into monosaccharides, disaccharides, trisaccharides, and tetrasaccharides. In conclusion, identifying a novel fucoidanase from the GH107 family expands the fucoidanase database and provides new opportunities for the comprehensive utilization of fucoidan.