This invention discloses a
sucrose isomerase site
mutant, a
genetically engineered bacterium, and a method for catalyzing the production of
isomaltulose. This invention utilizes PROSS
online analysis combined with
sequence alignment analysis to screen key
amino acid sites related to catalytic activity in
sucrose isomerases. Through site-
directed mutagenesis, the
mutant WT-Gro7-Q474T was obtained, with a maximum
specific enzyme activity of 683 U / mg. k cat (s ‑1 The concentration reached 718. By optimizing
protein expression conditions, including temperature, IPTG concentration, bacterial concentration, and time, and combining this with the method of co-expression of molecular chaperone proteins, a highly efficient
heterologous expression
system for
sucrose isomerase was established. This invention established an optimal
isomaltulose-catalyzed
reaction system: in a 2 L reactor, with 1 L of reaction solution and a
substrate concentration of 800 g / L sucrose, after 6 hours of reaction, all sucrose was converted, yielding
isomaltulose 792.50 g / L, with a conversion rate >99.5%.