Designing of a novel dextransucrase efficient in synthesizing oligosaccharides.

Dextransucrase (EC2.4.5.1) from strain Leuconostoc mesenteroides 0326, which synthesizes dextran and oligosaccharides, which act as prebiotics, are popularly used in such industries as food and medicine. A novel dextransucrase efficient in synthesizing oligosaccharides was designed. We constructed the truncation mutant DSR-S1-ΔA (residues 1-3087bp) by deleting the 1494bp fragment of the C-terminal. The novel enzyme (MW: 110kDa) loss activity, when sucrose was used as only substrate. After adding an acceptor, DSR-S1-ΔA was fully activated but with heavily impaired polysaccharide synthesis ability. Instead, the enzyme produced a large amount of oligosaccharides. DSR-S1-ΔA showed transglycosylation for synthesizing more oligosaccharides of lower degree of polymerization (DP) with different acceptors, and it also improved the selection range of dextransucrase acceptor response to acceptors. The enzyme developed in this study can be applied in glycodiversifcation studies.