Application of sucrose synthase from rice grains for the synthesis of carbohydrates.

The enzymatic synthesis of oligosaccharides offers an efficient way to obtain
regiospecific and stereo-selective natural and nonnatural target molecules. However,
the very expensive activated sugars are required as substrates for glycosyltransferases.
Activated sugars are usually synthesized by pyrophosphorylases from nucleoside
triphosphates and sugar-l-phosphates.'.* For cyclic in situ regeneration, at least
three enzymes are needed, which makes the synthesis of, for example, N-acetyllactosamine
very complex by established procedure. We report here on the
enzymatic synthesis of saccharides and activated sugars by the plant glycosyltransferase
sucrose synthase (EC 2.4.1.13)! The glycosyltransferase has the unique feature
of catalyzing in vitro the synthesis and cleavage of sucrose (SCHEME1 ). The main
advantage of sucrose synthase over pyrophosphorylases is the utilization of nucleoside
diphosphates (NDP) instead of nucleoside triphosphates to generate activated
sugars.