Purification and Properties of Thermostable Fucoidanase Produced by Recently Isolated Terrestrial Aspergillus flavus FS018

n this study fucoidanase produced by terrestrial Apsergillus flavus FS018 was purified and characterized. The pure fucoidanase enzyme was found to have an optimum activity of 20.8U/mL at 55 ºC and optimum activity of 17.2U/mL at pH 5.0. Furthermore, the fucoidanase retained 96% of its activity after 8 hours of incubation at 55 ºC. Metal ions such Mg2+ and Ca2+ ions were found to slightly enhance the activity of this enzyme while Na+, K+ had inhibitory effect on the activity. The enzyme was found to be active towards fucoidan consisting of α-1→4 and α-1→3 glycoside bonds in the main chains and also galactofucans group. Estimation of the kinetic parameters of the enzyme revealed that Km and Vmax to be 1.9 mM and 0.38 mg/min, respectively when fucoidan from Sargassum vulgare was used as substrate. SDS-PAGE analysis of the purified enzyme revealed that it’s a monomeric enzyme molecule with an estimated molecular weight of 70 kDa.