Accepted name: 3-(aryl)acrylate reductase
Reaction: (1) phloretate + electron-transfer flavoprotein = 4-coumarate + reduced electron-transfer flavoprotein
(2) 3-phenylpropanoate + electron-transfer flavoprotein = trans-cinnamate + reduced electron-transfer flavoprotein
(3) 3-(1H-indol-3-yl)propanoate + electron-transfer flavoprotein = 3-(indol-3-yl)acrylate + reduced electron-transfer flavoprotein
Glossary: phloretate = 3-(4-hydroxyphenyl)propanoate
crotonate = (2E)-but-2-enoate
Other name(s): acdA (gene name)
Systematic name: 3-(phenyl)propanoate:electron-transfer flavoprotein 2,3-oxidoreductase
Comments: The enzyme, found in some amino acid-fermenting anaerobic bacteria, participates in the fermentation pathways of L-phenylalanine, L-tyrosine, and L-tryptophan. Unlike EC, 2-enoate reductase, this enzyme has minimal activity with crotonate.
1.  Dodd, D., Spitzer, M.H., Van Treuren, W., Merrill, B.D., Hryckowian, A.J., Higginbottom, S.K., Le, A., Cowan, T.M., Nolan, G.P., Fischbach, M.A. and Sonnenburg, J.L. A gut bacterial pathway metabolizes aromatic amino acids into nine circulating metabolites. Nature 551 (2017) 648–652. [PMID: 29168502]
[EC created 2019]
Accepted name: phloretin hydrolase
Reaction: phloretin + H2O = phloretate + phloroglucinol
Glossary: phloretin = 3-(4-hydroxyphenyl)-1-(2,4,6-trihydroxyphenyl)propan-1-one
phloretate = 3-(4-hydroxyphenyl)propanoate
phloroglucinol = benzene-1,3,5-triol
Other name(s): ErPhy; lactase-phlorerin hydrolase; C-acylphenol hydrolase; 2′,4,4′,6′-tetrahydroxydehydrochalcone 1,3,5-trihydroxybenzenehydrolase (incorrect)
Systematic name: phloretin acylhydrolase (phloroglucinol-forming)
Comments: Also hydrolyses other C-acylated phenols related to phloretin. Isolated from the fungus Aspergillus niger and the bacteria Pantoea agglomerans and Eubacterium ramulus.
1.  Chatterjee, A.K. and Gibbins, L.N. Metabolism of phloridzin by Erwinia herbicola: nature of the degradation products, and the purification and properties of phloretin hydrolase. J. Bacteriol. 100 (1969) 594–600. [PMID: 5354935]
2.  Minamikawa, T., Jayasankar, N.P., Bohm, B.A., Taylor, I.E. and Towers, G.H. An inducible hydrolase from Aspergillus niger, acting on carbon-carbon bonds, for phlorrhizin and other C-acylated phenols. Biochem. J. 116 (1970) 889–897. [PMID: 5441377]
3.  Schoefer, L., Braune, A. and Blaut, M. Cloning and expression of a phloretin hydrolase gene from Eubacterium ramulus and characterization of the recombinant enzyme. Appl. Environ. Microbiol. 70 (2004) 6131–6137. [PMID: 15466559]
[EC created 1972, modified 2018]