racemase and epimerase activity, acting on carbohydrates and derivatives GDP-mannose 3,5-epimerase activity https://github.com/geneontology/go-ontology/issues/23098 https://github.com/geneontology/go-ontology/issues/30193 MetaCyc:RXN-7772 Catalysis of the reaction: GDP-mannose = GDP-L-galactose. GDP-D-mannose:GDP-L-galactose epimerase activity GDPmannose 3,5-epimerase activity guanosine 5'-diphosphate D-mannose:guanosine 5'-diphosphate L-galactose epimerase activity molecular_function RHEA:63800 RHEA:63804 GO:0047918 EC:5.1.3.18