Enzyme

1.2.1.8 - Betaine-aldehyde dehydrogenase

Alternative Name(s)
  • Betaine aldehyde dehydrogenase.
  • Betaine aldehyde oxidase.
  • BADH.

Catalytic Activity

betaine aldehyde + H2O + NAD(+) = betaine + 2 H(+) + NADH

Cofactors

There are no Cofactors for this Enzyme

Reaction Mechanism

    betaine-aldehyde dehydrogenase By Reference

    Aldehyde dehydrogenases (ALDHs) catalyse the irreversible oxidation of a broad range of aldehydes to the corresponding acids. The substrates that ALDH work on include aliphatic and aromatic aldehydes, but also 2-enoic, 2-hydroxy, and 2-halogenated aldehydes. ALDHs are important components of cellular pathways that metabolise aldehydes and they have been ascribed important functions in cellular detoxification and defence systems.

    Cys297 initiates a nucleophilic attack on the carbonyl carbon of betaine aldehyde, giving a negatively charged tetrahedral transition state. This is stabilised by the oxyanion hole. The oxyanion collapses and a hydride ion is transferred to NAD+. A hydroxide ion initiates a nucleophilic attack on the carbonyl of the now covalently bound substrate, again forming an oxyanion. When this collapses, the substrate-enzyme bond is broken.
    Catalytic Residues
    AA Uniprot Uniprot Resid PDB PDB Resid
    Asn P56533 166 1a4s 166
    Glu P56533 263 1a4s 263
    Glu P56533 477 1a4s 477
    Cys P56533 297 1a4s 297
    Step Components

    inferred reaction step, hydride transfer, aromatic bimolecular nucleophilic addition, enzyme-substrate complex formation, bimolecular nucleophilic addition, proton transfer, enzyme-substrate complex cleavage, native state of enzyme regenerated, unimolecular elimination by the conjugate base

    Step 1.

    Cys297 initiates a nucleophilic attack on the carbonyl carbon of betaine aldehyde in an addition reaction.

    Step 2.

    The oxyanion collapses, eliminating a hydride ion, which adds to NAD.

    Step 3.

    Glu263 deprotonates water, which initiates a nucleophilic attack on the carbonyl carbon of the covalently bound substrate in an addition reaction.

    Step 4.

    The oxyanion collapses, eliminating Cys297.

    Step 5.

    Water deprotonates Glu263 in an inferred return step.

    Products.

    The products of the reaction.

Reaction Parameters

  • Kinetic Parameters
    Organism KM Value [mM] Substrate Comment
    Spinacia oleracea 22 NAD+ mutant enzyme A441F, at pH 8.0 and 30°C
    Lycium ruthenicum 0.006 Betaine aldehyde pH 8.0, 30°C, recombinant isozyme LrAMADH1
    Staphylococcus aureus 0.053 Betaine aldehyde mutant enzyme V288D, at pH 8.0 and 30°C
  • Temperature
    Organism Temperature Range Comment
    Limulus polyphemus 20 - 40 20°C: about 45% of maximal activity, 40°C: about 70% of maximal activity
    Leymus chinensis 30 assay at
  • pH
    Organism pH Range Comment
    Spinacia oleracea 7 - 9 pH 7.0: about 40% of maximal activity, pH 9.0: about 50% of maximal activity
    Pseudomonas aeruginosa 7 - 9.5 pH 7.0: about 50% of maximal activity, pH 9.5: about 75% of maximal activity
    Limulus polyphemus 7 - 8 pH 7.0: about 35% of maximal activity, pH 8.0: about 70% of maximal activity
    Leymus chinensis 7.8 - 10.1 assay at

Associated Proteins

Protein name Organism
NAD/NADP-dependent betaine aldehyde dehydrogenase Escherichia coli (strain K12)
Betaine aldehyde dehydrogenase 2 Rice
Betaine aldehyde dehydrogenase, chloroplastic Prince-of-Wales feather
NAD/NADP-dependent betaine aldehyde dehydrogenase 1 Ensifer meliloti
Betaine aldehyde dehydrogenase 1 Rice

Citations