Tautomerase that converts enol-oxaloacetate, a strong inhibitor of succinate dehydrogenase, to the physiological keto form of oxaloacetate (PubMed:38287013). It is thereby required to maximize aerobic respiration efficiency by preventing succinate dehydrogenase inhibition (PubMed:38287013). . This is the function of FAHD2B (fumarylacetoacetate hydrolase domain containing 2B, Ensembl gene identifier ENSG00000144199).