INVESTIGATION OF SUCROSE SYNTHASE FROM RICE FOR THE SYNTHESIS OF VARIOUS NUCLEOTIDE SUGARS AND SACCHARIDES

The unique character of the plant glucosyltransferase sucrose synthase , to catalyse in vitro the synthesis and cleavage of sucrose under app ropriate conditions, can be exploited for the enzymatic synthesis of c arbohydrates. The present paper describes the potential utilization of sucrose synthase from rice for the enzymatic synthesis of activated s ugars and saccharides. In the cleavage reaction of sucrose, the nucleo side diphosphates can be used in the order UDP > TDP > ADP > CDP > GDP to obtain the corresponding activated glucoses. In batch reactions, > 90% conversion of UDP and TDP could be achieved. Substituting differe nt di- and trisaccharides for sucrose in the cleavage reaction with UD P 2-deoxysucrose was the most promising substrate. Sucrose synthase wa s combined with UDP-galactose 4'-epimerase and beta1-4 galactosyltrans ferase to synthesize N-acetyllactosamine with in situ regeneration of UDP-glucose. In the synthesis reaction of sucrose synthase, different donor (UDP-sugars) and acceptor substrates were investigated. UDP-N-ac etytglucosamine and UDP-xylose could be used in combination with fruct ose as acceptor. D-Xylulose, D-tagatose, D-lyxose, D-psicose, L-sorbos e, D-mannose, L-arabinose, 1,6 anhydroglucose, lactulose, raffinose an d isomaltulose can serve as acceptors for UDP-glucose.