LAUSR

BACKGROUND Alginate oligosaccharides (AOS) with various physiological activities have been widely used in food, agriculture and pharmaceutical industries. Compared with the physical and chemical method, the biological enzymatic method by alginate lyase has more advantages. Therefore, it is very important to clone and heterologously express alginate lyase. RESULTS A novel alginate lyase BY17PV7 from Microbulbifer sp. BY17 isolated from Gracilaria was cloned and expressed in E. coli BL21(DE3). BY17PV7 was about 27 KDa. BY17PV7 showed the highest activity (150.42±3.32 U/mg) at 43°C and pH 8.9, which could be obviously activated by Ca2+ , Mn2+ , Co2+ , Fe3+ , Na+ , and inhibited by Mg2+ , Zn2+ , Ba2+ , Cu2+ , SDS, EDTA. BY17PV7 had a wide range of substrate specificity and a good degradation activity for polyM and polyG, demonstrating that it was a bifunctional alginate lyase. Meanwhile, Kinetic parameters showed that BY17PV7 had a higher affinity for polyG. BY17PV7 released AOS with a degree of polymerization (DP) of 3-4 in an endolytic manner from sodium alginate. AOS showed the great antioxidant ability of reducing Fe3+ and scavenging radicals such as hydroxyl, ABTS+ and DPPH. CONCLUSION A novel bifunctional alginate lyase BY17PV7 was expressed and characterized in E. coli BL21(DE3). The results were helpful to analyze the molecular mechanisms of degrading patterns in the polysaccharide lyase (PL) family 7. This article is protected by copyright. All rights reserved.