ENZYME

ENZYME entry: EC 4.99.1.7

Accepted Name

Phenylacetaldoxime dehydratase.

Alternative Name(s)

Arylacetaldoxime dehydratase.

PAOx dehydratase.

Reaction catalysed

(Z)-phenylacetaldehyde oxime <=> phenylacetonitrile + H(2)O

Cofactor(s)

Heme.

Comment(s)

The enzyme from Bacillus sp. OxB-1 contains protoheme IX, the iron of which must be in the form Fe(2+) for activity.
(Z)-phenylacetaldoxime binds to ferric heme (the Fe(3+) form) via the oxygen atom whereas it binds to the active ferrous form via the nitrogen atom.
In this way, the oxidation state of the heme controls the coordination stucture of the substrate--heme complex, which regulates enzyme activity.
The enzyme is active toward several (Z)-arylacetaldoximes and (E/Z)- alkylaldoximes as well as toward arylalkylaldoximes such as 3-phenylpropionaldoxime and 4-phenylbutyraldoxime.
However, it is inactive with phenylacetaldoximes that have a substituent group at an alpha-site of an oxime group, for example, with (E/Z)-2-phenylpropionaldoxime and (E/Z)-mandelaldoxime.
The activity of the enzyme is inhibited completely by the heavy-metal cations Cu(+), Cu(2+), Ag(+) and Hg(+) whereas Fe(2+) and Sn(2+) have an activatory effect.

Cross-references

BRENDA

EC2PDB

ExplorEnz

PRIAM enzyme-specific profiles

KEGG Ligand Database for Enzyme Nomenclature

IUBMB Enzyme Nomenclature