Characterization and Application of Recombinant Sucrose Synthase 1 from Potato for the Synthesis of Sucrose Analogues

The characteristics and application of recombinant sucrose synthase 1 (SuSy1) from potato for the synthesis of sucrose analogues are described. With UDP-Glc as donor substrate SuSy1 accepts a variety of ketoses, e.g. 1-deoxy-1-fluoro-D-fructose (100%), D-psicose (7%), L-sorbose (18%) and D-xylulose (7%), as well as aldoses, e.g. D-lyxose (22%) and L-mannose (16%). The enzyme also shows a flexible the donor substrate spectrum with acceptance of UDP-GlcNAc (100%), UDP-GlcA (32%), UDP-Gal (23%), UDP-GalNAc (6%) and UDP-Xyl (39%). The kinetic analysis revealed a substrate inhibition by UDP-Glc with a Km- and KiS-value of 0.46 mM and 2.25 mM, respectively and a Vmax of 21.76 U/mg. A substrate inhibition was also obtained for D-fructose with a Km- and a KiS-value of 2.05 mM and 35.88 mM, respectively, and a Vmax of 10.63 U/mg at a constant concentration of 2 mM UDP-Glc. Susy1 was used for the preparative synthesis of 1´-deoxy-1´-fluoro- b-Dfructofuranosyl- a-D-glucopyranoside and [13C1]-b-D-fructofuranosyl-a-D-glucopyranoside. Both products were characterized by 1H-, 13CNMR and in case of of 1´-deoxy-1´-fluoro-b-D-fructofuranosyl-a-D-glucopyranoside also with 19F-NMR.