High yield synthesis of nigerooligosaccharides by transglycosylation catalyzed by α-glucosidase TaAglA from Thermoplasma acidophilum

Nigerooligosaccharides (NOS) is a new functional oligosaccharide containing alpha-1,3 glucosidic bond with good anti-digestive properties and intestinal probiotics. Transglycosylation catalyzed by alpha-glucosidase is an effective method for the preparation of oligosaccharides. However, there are few reports on the enzymatic synthesis of nigerooligosaccharides by alpha-glucosidase at present. This study was aimed to investigate the transglycosylation property of the GH31 alpha-glucosidase from Thermoplasma acidophilum, TaAglA, and also evaluate its application performance in the preparation of NOS. It was found that TaAglA exhibited selectivity for alpha-1,3 and alpha-1,4 linkages when catalyzing hydrolysis, but for alpha-1,3 and alpha-1,6 linkages when catalyzing transglycosylation. Using 10% glucose and 20% maltose as substrates, TaAglA yielded 88.5 g/L NOS under the condition of pH 6.0, 80 degrees C and 1 U/mL enzyme addition, which was the highest level to our knowledge. In addition, components with higher polymerization degrees, i.e. nigerotriose and nigerosyl-glucose, occupied 53.6% proportion of the total NOS products, giving it better probiotic functions. Futhermore, after purification by glucoamylase digestion and yeast culture, the final yield of NOS was 26.1%, and the purity of the product was 93%. These findings on TaAglA were expected to provide a new candidate for large-scale enzymatic synthesis of NOS, and also have important theoretical significance for the study of GH31 alpha-glucosidase.

Automated summary

This study aimed to investigate the transglycosylation property of the GH31 alpha-glucosidase from Thermoplasma acidophilum and evaluate its application performance in the preparation of Nigerooligosaccharides (NOS). The results showed that the enzyme exhibited selectivity for different linkages during hydrolysis and transglycosylation. Using glucose and maltose as substrates, the enzyme yielded high levels of NOS with good purity. These findings provide a new candidate for large-scale enzymatic synthesis of NOS and have important theoretical significance for the study of GH31 alpha-glucosidase.