GDP-mannose 3,5-epimerase
In enzymology, a GDP-mannose 3,5-epimerase is an enzyme that catalyzes the chemical reaction
Hence, this enzyme has one substrate, GDP-mannose, and two products, GDP-L-galactose and GDP-L-gulose
Since only GDP-L-gulose was found in the reaction mixture, it was postulated that the enzyme performs the C5-epimerization prior to the C3-epimerization. However, GDP-D-altrose was recently found as a reaction product, which means that both reaction routes can occur: C5-prior-to-C3 and C3-prior-to-C5.
This also means that the GDP-mannose 3,5-epimerase has three reaction products, namely the main product GDP-L-galactose and two sideproducts GDP-L-gulose + GDP-D-altrose.
This enzyme belongs to the family of isomerases, specifically those racemases and epimerases acting on carbohydrates and derivatives. The systematic name of this enzyme class is GDP-mannose 3,5-epimerase. Other names in common use include GDP-D-mannose:GDP-L-galactose epimerase, guanosine 5'-diphosphate D-mannose:guanosine 5'-diphosphate, GM35E, and L-galactose epimerase. This enzyme participates in ascorbate and aldarate metabolism.