Polyamine oxidases catalyse the oxidation of
polyamines and acetylpolyamines and are responsible for the
polyamine interconversion metabolism in animal cells.
Polyamine oxidases from yeast can oxidize
spermine,
N(1)-acetylspermine, and
N(1)-acetylspermidine, while in vertebrates two different
enzymes, namely
spermine oxidase and acetylpolyamine
oxidase, specifically catalyse the oxidation of
spermine, and N(1)-acetylspermine/N(1)-acetylspermidine, respectively. In this work we proved that the specialized vertebrate
spermine and acetylpolyamine
oxidases have arisen from an ancestor invertebrate
polyamine oxidase with lower specificity for
polyamine substrates, as demonstrated by the enzymatic activity of the mollusc
polyamine oxidase characterized here. This is the first report of an invertebrate
polyamine oxidase, the Pacific oyster Crassostrea gigas (CgiPAO), overexpressed as a
recombinant protein. This
enzyme was biochemically characterized and demonstrated to be able to
oxidase both
N(1)-acetylspermine and
spermine, albeit with different efficiency. Circular dichroism analysis gave an estimation of the secondary structure content and modelling of the three-dimensional structure of this
protein and docking studies highlighted active site features. The availability of this pluripotent
enzyme can have applications in crystallographic studies and
pharmaceutical biotechnologies, including anticancer
therapy as a source of
hydrogen peroxide able to induce
cancer cell death.