Optimization of leucrose production by dextransucrase from Streptococcus mutans and its application as an adipogenesis regulator

Leucrose is a sucrose isomer which has an α-1,5-linkage, and slowly hydrolyzed to glucose and fructose by small intestinal α-glucosidases. Leucrose can be produced by an isomerization reaction of dextransucrase on a sucrose substrate. In this study, the recombinant dextransucrase from Streptococcus mutans (SmDS) was applied to optimize the reaction conditions for leucrose production. With a substrate mixture of 0.5 M sucrose + 1.0 M fructose, the greatest yield (ca. 24.5%) of leucrose was obtained by SmDS treatment at 30 °C for 120 h. When preadipocyte 3T3-L1 cells were treated with leucrose, this disaccharide inhibited intracellular lipid accumulation in a dose-dependent manner and significantly suppressed mRNA levels of major adipogenic genes, including CCAT/enhancer-binding protein α (C/EBPα), peroxisome proliferator-activated receptor-γ (PPARγ), fatty acid synthase (FAS), and sterol regulatory element-binding protein-1C (SREBP-1C). Phosphorylation of PI3 kinase/Akt/mTOR was also reduced with leucrose treatment. These results suggest that leucrose has a potential in regulating adipogenesis.