Structures of heterooligosaccharides synthesized by levansucrase.

In the presence of excess amounts of various monosaccharides as acceptors, Bacillus subtilis levansucrase synthesized various heterooligosaccharides as a result of transfer of the fructosyl residue from sucrose. The saccharides produced in the presence of D-glucose, D-mannose, and D-xylose were all non-reducing disaccharides and were identified as beta-D-fructofuranosyl-alpha-D-glucopyranoside (sucrose), beta-D-fructo-furanosyl-alpha-D-mannopyranoside (mannosucrose), and beta-D-fructofuranosyl-alpha-D-xylopyranoside (xylsucrose), respectively. The saccharides produced in the presence of D-galactose were also non-reducing, but consisted of di-, tri-, and tetrasaccharides. The di- and trisaccharides were galsucrose and 6F-beta-D-fructofuranosyl-galsucrose. The saccharide synthesized in the presence of L-arabinose was a reducing saccharide and was determined to be 4-O-beta-D-fructofuranosyl-L-arabinose. In the presence of D-fructose, several reducing levan oligomers, levanbiose, levantriose, levantetraose, etc., were produced, which were not observed in the synthesis of levan from sucrose alone.