An epimerase-reductase in L-fucose synthesis.
The first committed enzyme in GDP-L-fucose formation from GDP-D-mannose is GDP-D-mannose 4,6-dehydratase, which forms GDP-4-keto-6-deoxy-D-mannose. The uncertain enzymatic steps beyond this point were examined in this study. Assays were developed for the epimerase and reductase activities which the putative pathway would predict. A protein was isolated exhibiting homogeneity by several criteria. This single protein, which forms GDP-L-fucose from GDP-4-keto-6-deoxy-D-mannose and NADH, appears to possess both epimerase and reductase capabilities and may be termed GDP-4-keto-6-deoxy-D-mannose-3,5-epimerase-4-reductase. Analysis on a molecular sieve column using fast protein liquid chromatography established a molecular weight of 63,100 for the native enzyme, whereas sodium dodecyl sulfate-polyacrylamide gel electrophoresis established a subunit molecular weight of 31,500.
Chang
S
S
Department of Biochemistry, Ohio State University, Columbus 43210-1292.
Duerr
B
B
Serif
G
G
D000818:Animals; D002238:Carbohydrate Epimerases / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005643:Fucose / Q000096:biosynthesis*; D006154:Guanosine Diphosphate Fucose / Q000378:metabolism; D006155:Guanosine Diphosphate Mannose / Q000031:analogs & derivatives*; D007658:Ketone Oxidoreductases; D007700:Kinetics; D008970:Molecular Weight; D009097:Multienzyme Complexes; D012210:Rhamnose / Q000031:analogs & derivatives* / Q000302:isolation & purification; D013401:Sugar Alcohol Dehydrogenases / Q000378:metabolism*; D013552:Swine; D013961:Thyroid Gland / Q000201:enzymology
D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; C110682:wcaG protein, E coli; D006154:Guanosine Diphosphate Fucose; C054686:GDP-4-keto-6-deoxymannose; D005643:Fucose; D006155:Guanosine Diphosphate Mannose; D013401:Sugar Alcohol Dehydrogenases; D007658:Ketone Oxidoreductases; D002238:Carbohydrate Epimerases; D012210:Rhamnose