Efficient synthesis of nigerose by a novel nigerose phosphorylase from Anaerosporobacter mobilis

Abstract

Nigerose is a kind of rare disaccharide connected by an α-1,3 glucosidic bond, which is a potential probiotic due to its antidigestive properties and beneficial functions. This study identified and characterized a novel GH65 glycoside phosphorylase derived from Anaerosporobacter mobilis (AmNP). This new protein could specifically catalyze the phospholysis of nigerose to generate glucose and glucose-1-phosphate in the presence of phosphate, indicating it was a typical nigerose phosphorylase. Compared to the previously reported nigerose phosphorylases, AmNP exhibited lower affinity towards nigerose in phosphorolysis reaction and higher affinity towards glucose in reverse phosphorolysis reaction, which indicated that AmNP might be superior in the synthetic capability of disaccharide. Then AmNP was employed to synergize with maltose phosphorylase from Lactobacillus brevis (LbMP) to catalyze the synthesis of nigerose using maltose as the substrate. After optimization of reaction conditions, the highest nigerose yield reached 132.0 g/L with a 66.3% conversion rate, which was higher than ever reported cases using the same reaction pathway to our knowledge. These findings on AmNP in this work were expected to provide a new candidate for large-scale enzymatic synthesis of nigerose and have important theoretical significance for studying nigerose phosphorylase.