The Donor Substrate Spectrum of Recombinant Sucrose Synthase 1 from Potato for the Synthesis of Sucrose Analogues

The donor substrate spectrum of recombinant sucrose synthase 1 (SuSy1) from potato was studied in order to synthesise novel sucrose analogues. With D‐fructose as acceptor substrate SuSy1 accepts a variety of UDP‐activated sugars, e.g., UDP‐N‐acetyl‐α‐D‐glucosamine (UDP‐GlcNAc, 2) (100%), UDP‐α‐D‐glucuronic acid (UDP‐GlcA, 3) (32%), UDP‐α‐D‐xylose (UDP‐Xyl, 4) (39%), UDP‐α‐D‐galactose (UDP‐Gal, 5) (23%), and UDP‐N‐acetyl‐α‐D‐galactosamine (UDP‐GalNAc, 6) (23%). The kinetic analyses revealed that the non‐natural donors 2 (kcat/Km 1.2 s−1 mM−1) and 5 (kcat/Km 0.01 s−1 mM−1) were relative poor substrates compared to UDP‐Glc 1 (kcat/Km 310.4 s−1 mM−1). UDP‐GlcNAc was used in a preparative synthesis to produce 188 mg (0.5 mmol) 2‐acetamido‐2‐deoxy‐D‐glucopyranosyl‐β‐D‐fructofuranoside (9). The sucrose analogue 9 was not hydrolysed by invertase.