Homologous (beta/alpha)8-barrel enzymes that catalyze unrelated reactions: orotidine 5'-monophosphate decarboxylase and 3-keto-L-gulonate 6-phosphate decar... Homologous (β/α) 8-barrel enzymes that catalyze unrelated reactions: orotidine 5'-monophosphate decarboxylase and 3-keto-l-gulonate 6-...