Characterization of L-fucose isomerase from Paenibacillus rhizosphaerae to produce L-fuculose from hydrolyzed fucoidan and commercial fucose

Background L-fuculose is an expensive and rare sugar used against different kinds of diseases such as HIV, anti-cancer, anti-viral, Hepatitis-B, human lysosomal disease (fucosidosis), and cardio-protective drugs. The enzymatic way of converting L-fucose into L-fuculose would be an effective method with great industrial applications. The purpose of this research is to introduce a high production of L-fuculose from cheap and natural sources (fucoidan) and commercially source (Sigma-Aldrich) by a recombinant enzyme L-fucose isomerase from Paenibacillus rhizosphaerae (Pa-LFI).Results Fucose containing polysaccharide (FPs) called fucoidan was extracted, hydrolyzed and characterized by U. pinnatifida for enzymatic production of L-fuculose. The FPs provide 35.9% of fucose along with few other monosaccharides. Pa-LFI was characterized and purified with a single band at 65 kDa. It showed an activity of 104.5 U mg -1 and exhibited as a hexamer with native molecular mass 396 kDa. The maximum activity for recombinant Pa-LFI was detected at pH 6.5 and 50 °C in 1 mM of Mn 2+ . The melting temperature observed 75 °C and half-life at 50 °C was 12.6 h. The isomerizing activity of Pa-LFI with aldose substrate (L-fucose) was higher exposing K m , k cat and k cat / K m 86.2 mM, 32831 min -1 and 335 min -1 mM -1 respectively. The conversion ratio of L-fuculose from 100 g L -1 of FPs and commercial fucose after the equilibrium state was about 6% (5.6 g L -1 ) and 30% (30.2 g L -1 ) respectively.Conclusion Pa-LFI catalyzed the reaction to convert L-fucose into L-fuculose. The enzyme will be helpful in the production of L-fuculose with an efficient and simple method without producing any by-product.