Reaction: (1) trans-4-hydroxy-L-proline betaine = cis-4-hydroxy-D-proline betaine
(2) L-proline betaine = D-proline betaine
Glossary: trans-4-hydroxy-L-proline betaine = (2S,4R)-4-hydroxy-1,1-dimethylpyrrolidinium-2-carboxylate
cis-4-hydroxy-D-proline betaine = (2R,4R)-4-hydroxy-1,1-dimethylpyrrolidinium-2-carboxylate
L-proline betaine = (2S)-1,1-dimethylpyrrolidinium-2-carboxylate
D-proline betaine = (2R)-1,1-dimethylpyrrolidinium-2-carboxylate
Other name(s): hpbD (gene name); Hyp-B 2-epimerase; (4R)-4-hydroxyproline betaine 2-epimerase
Systematic name: 4-hydroxyproline betaine 2-epimerase
Comments: The enzyme, characterized from the bacteria Pelagibaca bermudensis and Paracoccus denitrificans, specifically catalyses racemization of trans-4-hydroxy-L-proline betaine and L-proline betaine at the C-2 position.
Links to other databases: BRENDA, EXPASY, ExplorEnz, KEGG, Metacyc, PDB, CAS registry number:
References:
1. Zhao, S., Kumar, R., Sakai, A., Vetting, M.W., Wood, B.M., Brown, S., Bonanno, J.B., Hillerich, B.S., Seidel, R.D., Babbitt, P.C., Almo, S.C., Sweedler, J.V., Gerlt, J.A., Cronan, J.E. and Jacobson, M.P. Discovery of new enzymes and metabolic pathways by using structure and genome context. Nature 502 (2013) 698-702. [PMID: 24056934]
2. Kumar, R., Zhao, S., Vetting, M.W., Wood, B.M., Sakai, A., Cho, K., Solbiati, J., Almo, S.C., Sweedler, J.V., Jacobson, M.P., Gerlt, J.A. and Cronan, J.E. Prediction and biochemical demonstration of a catabolic pathway for the osmoprotectant proline betaine. MBio 5 (2014) e00933. [PMID: 24520058]