Direct production of allitol from d-fructose by a coupling reaction using d-tagatose 3-epimerase, ribitol dehydrogenase and formate dehydrogenase

Abstract

Allitol was produced from d-fructose via a new NADH-regenerating enzymatic reaction system using d-tagatose 3-epimerase ( d-TE), ribitol dehydrogenase (RDH), and formate dehydrogenase (FDH). d-Fructose was epimerized to d-psicose by the d-TE of Pseudomonas cichorii ST-24 and the d-psicose was subsequently reduced to allitol by the RDH of an RDH-constitutive mutant, X-22, derived from Klebsiella pneumoniae IFO 3321. NADH regeneration for the reduction of d-psicose by the RDH was achieved by the irreversible formate dehydrogenase reaction, which allowed the d-psicose produced from d-fructose to be successively transformed to allitol with a production yield from d-fructose of almost 100%. The reactions progressed without any by-product formation. After separation of the product from the reaction mixture by a simple procedure, a crystal of allitol was obtained in a yield exceeding 90%. This crystal was characterized and determined to be allitol by HPLC analysis, its IR and NMR spectra, its melting point, and optical rotation measurement.