Overview for MACiE Entry M0274
EC Number: 126.96.36.199 (A member of the Oxidoreductases, Acting on the aldehyde or oxo group of donors, With oxygen as acceptor)
Enzyme Name: pyruvate oxidase
Biological Species: Lactobacillus plantarum (Lactobacillus plantarum)
Catalytic Chain UniprotKB Accession Codes:
Representative PDB Code: 1pow - THE REFINED STRUCTURES OF A STABILIZED MUTANT AND OF WILD-TYPEPYRUVATE OXIDASE FROM LACTOBACILLUS PLANTARUM (Resolution = 2.50 Å).
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Overall Comment: An alternative mechanism involving a transient radical cation has been proposed based on the same evidence present in the cited references.
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Stepwise Description of the Reaction
|Step 1||Glu59' deprotonates the thiamine diphosphate cofactor at the N1 position. This initiates double bond rearrangement which results in the deprotonation of the N=CH-S group. This activates the cofactor towards electrophilic attack.|
|Step 2||The carbanion of thiamine diphosphate initiates a nucleophilic attack on the carbonyl carbon of pyruvate in an addition reaction. The conjugated double bond system of the cofactor undergoes rearrangement which results in the deprotonation of Glu59'.|
|Step 3||The covalently bound pyruvate undergoes decarboxylation.|
|Step 4||A single electron is transferred from the high energy thamine diphosphate enamine intermediate to the FAD, resulting in bond order rearrangement and deprotonation of the alcohol group present on the intermediate.|
|Step 5||Tautomerisation of the resulting radical intermediate.|
|Step 6||The thiamine ring nitrogen acts as an electron sink in the formation of the radical tautomer.|
|Step 7||Phosphate initiates a nucleophilic attack on the kinetically stable anion radical adduct.|
|Step 8||The high energy phosphate radical delivers a second reducing equivalent to the FAD semiquinone.|
|Step 9||The tetrahedral anion intermediate collapses. This forms the high energy metabolite acetyl-phosphate.|
|Step 10||The FAD diradical transfers one of its electrons to dioxygen with subsequent loss of a single proton.|
|Step 11||The FADH transfers the second radical and proton to the dioxygen to regenerate the FAD cofactor and hydrogen peroxide.|
|Step 12||The TTP cofactor is regenerated by reprotonation of the C2 position.|
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Catalytic Residues Involved
||Location of Function
Organic Cofactors for M0274
Metal Cofactors for M0274
- K. Tittmann et al. (2000), Biochemistry, 39, 10747-10754. Mechanism of elementary catalytic steps of pyruvate oxidase from Lacobacillus plantarum.
- G. Wille et al. (0), Biochemistry, 44, 5086-5094. .
- G. Wille et al. (2006), Nat. Chem. Biol., 2, 324-328. The catalytic role of a thiamin diphosphate enzyme examined by crystallography.
- K. Tittmann et al. (2009), FEBS Journal, 276, 2454-2468. Reaction mechanisms of thiamin diphosphate enzymes: redox reactions.
- Y. A. Muller et al. (1994), J. Mol. Biol., 237, 315-335. The refined structures of a stabilized mutant and of wild-type pyruvate oxidase from Lactobacillus plantarum.
- K. Tittmann et al. (1998), J. Biol. Chem., 273, 12929-12934. Activation of thiamin diphosphate and FAD in the phosphate dependent pyruvate oxidase from Lactobacillus plantarum.
Homologue information for M0274 (1pow)
MACiE Homologues (within the PDB)
MACiE Homologues (within UniprotKB/SwissProt)
Entries with at least one Catalytic CATH code in common (different mechanisms):
|M0106 ||pyruvate dehydrogenase (acetyl-transferring) |
|M0280 ||3-methyl-2-oxobutanoate dehydrogenase (2-methylpropanoyl-transferring) |
|M0119 ||pyruvate:ferredoxin oxidoreducatse |
|M0219 ||transketolase |
|M0289 ||acetolactate synthase |
|M0215 ||pyruvate decarboxylase |
|M0220 ||benzoylformate decarboxylase |
|M0221 ||benzoin aldolase |
View a comparison of the other reactions in MACiE with the CATH domain 188.8.131.520
Links to this entry in other databases