Enzymatic synthesis of l-tagatose from galactitol with galactitol dehydrogenase from Rhodobacter sphaeroides D

The rare sugar l-tagatose was prepared with an overall yield of 78% by enzymatic C-5 oxidation of galactitol with co-substrate regeneration, and purification by ligand exchange chromatography. The sugar was identified by HPLC, melting point determination, optical rotation, and NMR spectrometry.