Levansucrases from Pseudomonas syringae pv. tomato and P. chlororaphis subsp. aurantiaca: Substrate specificity, polymerizing properties and usage of different acceptors for fructosylation

Levansucrases of Pseudomonas syringae pv. tomato DC3000 (Lsc3) and Pseudomonas chlororaphis subsp. aurantiaca (also Pseudomonas aurantiaca) (LscA) have 73% identity of protein sequences, similar substrate specificity and kinetic properties. Both enzymes produce levan and fructooligosaccharides (FOS) of varied length from sucrose, raffinose and sugar beet molasses. A novel high-throughput chip-based nanoelectrospray mass spectrometric method was applied to screen alternative fructosyl acceptors for levansucrases. Lsc3 and LscA could both transfructosylate D-xylose, D-fucose, L- and D-arabinose, D-ribose, D-sorbitol, xylitol, xylobiose, D-mannitol, D-galacturonic acid and methyl-α-D-glucopyra…