Purification and characterization of polysaccharides degradases produced by Alteromonas sp. A321

•Two degradase for PE were purified and characterized.•Rha1(SO3H)1, Rha1(SO3H)1Gluc1, and Rha2(SO3H)2Gluc1 were first reported.•The degrade products provide information for the elucidation of PE structure

Two different degradases from Alteromonas sp. A321for polysaccharides from Enteromorpha prolifera (DPE-L and DPE-P) were purified to homogeneity. The molecular weights of purified DPE-L and DPE-P were 75.2 and 102.5 kDa, respectively, and their internal sequences were analysed by LC–MS–MS. The enzymes exhibited an optimum temperature of 30–40 °C (DPE-L) and 35–45 °C (DPE-P), an optimum pH of 7.0 (DPE-L) and 6.0 (DPE-P). DPE-P was highly stable in the presence of EDTA and 1,10-phenanthroline while DPE-L was inhibited by 1,10-phenanthroline. The Km values of DPE-L and DPE-P were 2.93 mg/ml and 0.31 mg/ml and the Vmax values were 6.11 μmol/min/ml and 2.88 μmol/min/ml, respectively. Results of HPLC and ESI-MS analyses showed that enzymatic products were: Rha1(SO3H)1, Rha1(SO3H)1Gluc1, Rha2(SO3H)2Gluc1, and Rha3(SO3H)3Gluc1Xyl1 by DPE-L, and Glu2, Glu3, plus Glu4 by DPE-P, respectively. Thus DPE-L and DPE-P can be used to produce oligosaccharides which potentially revealed more of structure of polysaccharides from E. prolifera.