title: The acarbose-biosynthetic enzyme AcbO from Actinoplanes sp. SE 50/110 is a 2-epi-5-epi-valiolone-7-phosphate 2-epimerase.
abstract: The C7-cyclitol 2-epi-5-epi-valiolone is the first precursor of the cyclitol moiety of the alpha-glucosidase inhibitor acarbose in Actinoplanes sp. SE50. The 2-epi-5-epi-valiolone becomes phosphorylated at C7 by the ATP dependent kinase AcbM prior to the next modifications. Preliminary data gave evidences that the AcbO protein could catalyse the first modification step of 2-epi-5-epi-valiolone-7-phosphate. Therefore, the AcbO protein, the encoding gene of which is also part of the acbKMLNOC operon, was overproduced and purified. Indeed the purified protein catalysed the 2-epimerisation of 2-epi-5-epi-valiolone-7-phosphate. The chemical structure of the purified reaction product was proven by nuclear magnetic resonance spectroscopy to be 5-epi-valiolone-7-phosphate.
authors.affiliation: Institute of Chemical Microbiology, Bergische University, Gauss-Str 20, D-42097 Wuppertal, Germany.
authors.forename: Chang-Sheng
authors.initials: CS
authors.lastname: Zhang
authors.forename: Michael
authors.initials: M
authors.lastname: Podeschwa
authors.forename: Hans-Josef
authors.initials: HJ
authors.lastname: Altenbach
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Piepersberg
authors.forename: Udo F
authors.initials: UF
authors.lastname: Wehmeier
mesh_terms: D020909:Acarbose / Q000378:metabolism*; D000192:Actinomycetales / Q000201:enzymology*; D002240:Carbohydrate Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D019998:Racemases and Epimerases / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification
chemical_list: D011993:Recombinant Fusion Proteins; D019998:Racemases and Epimerases; D020909:Acarbose