Reaction: L-mimosine + H2O = 3-hydroxy-4H-pyrid-4-one + pyruvate + NH3 (overall reaction)
(1a) L-mimosine = 3-hydroxy-4H-pyrid-4-one + 2-aminoprop-2-enoate
(1b) 2-aminoprop-2-enoate = 2-iminopropanoate (spontaneous)
(1c) 2-iminopropanoate + H2O = pyruvate + NH3 (spontaneous)
Glossary: L-mimosine = (2S)-2-amino-3-[3-hydroxy-4-oxopyridin-1(4H)-yl]propanoate
Other name(s): mimosine amidohydrolase (incorrect)
Systematic name: (2S)-2-amino-3-[3-hydroxy-4-oxopyridin-1(4H)-yl]propanoate 3-hydroxy-4H-pyrid-4-one-lyase (2-aminoprop-2-enoate-forming)
Comments: A pyridoxal-phosphate protein. The enzyme degrades the toxic amino acid L-mimosine. It cleaves a carbon-nitrogen bond, releasing 3-hydroxy-4H-pyrid-4-one and an unstable enamine product that tautomerizes to an imine form, which undergoes a hydrolytic deamination to form pyruvate and ammonia. It is thought to have evolved from EC 4.4.1.13, cysteine-S-conjugate β-lyase. It has been described in both mimosine-producing plants and some bacteria.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Tangendjaja, B., Lowry, J.B. and Wills, R.H. Isolation of a mimosine degrading enzyme from Leucaena leaf. J. Sci. Food Agric. 37 (1986) 523-526.
2. Negi, V.S., Bingham, J.P., Li, Q.X. and Borthakur, D. A carbon-nitrogen lyase from Leucaena leucocephala catalyzes the first step of mimosine degradation. Plant Physiol. 164 (2014) 922-934. [PMID: 24351687]
3. Oogai, S., Fukuta, M., Watanabe, K., Inafuku, M. and Oku, H. Molecular characterization of mimosinase and cystathionine β-lyase in the Mimosoideae subfamily member Mimosa pudica. J. Plant Res. 132 (2019) 667-680. [PMID: 31368041]
4. Oogai, S., Fukuta, M., Inafuku, M. and Oku, H. Isolation and characterization of mimosine degrading enzyme from Arthrobacter sp. Ryudai-S1. World J. Microbiol. Biotechnol. 38 (2022) 172. [PMID: 35908235]