title: A novel carbohydrate:acceptor oxidoreductase from Microdochium nivale.
abstract: A Microdochium nivale carbohydrate:acceptor oxidoreductase was purified, cloned, heterologously expressed, and characterized. The gene encoding the protein showed one intron, and the ORF showed a sequence with low homology (< or = 25% identity or 65% similarity) to other known flavin-containing carbohydrate oxidases. The maturation of the protein required the cleavage of a tetrameric propeptide in addition to an 18 amino-acid signal peptide. The enzyme was found to have a relative molecular mass of 55 000 Da, an isoelectric point of 9, and one FAD per protein. It could oxidize mono-, oligo-, or polymeric saccharides, and transfer their electrons to O2 or other acceptors. When D-glucose served as electron-donating substrate, an activity of 2 s(-1) was observed at pH 5.5 and 23 degrees C. Among various oligosaccharides, the enzyme preferred tetrameric dextrins, indicating a favorable interaction of four linked glucose units with the substrate pocket. The unique structure and ability of oxidizing oligo/polymeric saccharides suggest a promising prospect of this enzyme for various industrial/medicinal applications.
authors.affiliation: Novo Nordisk Biotech, Inc., Davis, CA, USA. fengxu@novoenzymesbiotech.com
authors.forename: F
authors.initials: F
authors.lastname: Xu
authors.forename: E J
authors.initials: EJ
authors.lastname: Golightly
authors.forename: C C
authors.initials: CC
authors.lastname: Fuglsang
authors.forename: P
authors.initials: P
authors.lastname: Schneider
authors.forename: K R
authors.initials: KR
authors.lastname: Duke
authors.forename: L
authors.initials: L
authors.lastname: Lam
authors.forename: S
authors.initials: S
authors.lastname: Christensen
authors.forename: K M
authors.initials: KM
authors.lastname: Brown
authors.forename: C T
authors.initials: CT
authors.lastname: Jørgensen
authors.forename: S H
authors.initials: SH
authors.lastname: Brown
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D002237:Carbohydrate Dehydrogenases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D050260:Carbohydrate Metabolism; D003001:Cloning, Molecular; D003912:Dextrins / Q000378:metabolism; D005656:Fungal Proteins; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D020037:Sordariales / Q000201:enzymology* / Q000235:genetics
chemical_list: D003912:Dextrins; D005656:Fungal Proteins; D000429:Alcohol Oxidoreductases; D002237:Carbohydrate Dehydrogenases; C423010:MnCO protein, Microdochium nivale