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