Spermine is taken up by mammalian mitochondria and this process needs to identify its catabolic pathway in such organelles. Therefore, the ability of purified bovine liver mitochondria for natural polyamine uptake was verified. The presence of an MDL 72527-sensitive enzyme, with spermine oxidase activity, in the matrix of bovine liver mitochondria was determined using a kinetic approach. Western blot analysis of mitochondrial fractions and immunogold electron microscopy observations of purified mitochondria unequivocally confirmed the presence of a protein recognized by anti-spermine oxidase antibodies in the mitochondrial matrix. Preliminary kinetic characterization showed that spermine is the preferred substrate of this enzyme; lower activity was detected with spermidine and acetylated polyamines. The considerable effect of ionic strength on the Vmax/KM ratio suggested the presence of more than one negatively charged zone inside the active site cavity of this mitochondrial enzyme and this proposes that the enzyme is probably involved in the docking of positively charged substrates. These findings indicate that the mitochondrial matrix of bovine liver contains an enzyme belonging to the spermine oxidase class. Because hydrogen peroxide is generated by spermine oxidase activity, the possible involvement of the latter as an important signaling transducer under both physiological and pathological conditions should be considered. This work was done in collaboration with the Department of Molecular Sciences and Nanosystems, ‘‘Ca’ Foscari’’ University of Venice.

Bovine liver mitochondria: constitutive presence of a novel enzyme with spermine oxidase properties

BONAIUTO, EMANUELA;MARTINIS, PAMELA;VIANELLO, FABIO;TONINELLO, ANTONIO;DI PAOLO, MARIA LUISA
2016

Abstract

Spermine is taken up by mammalian mitochondria and this process needs to identify its catabolic pathway in such organelles. Therefore, the ability of purified bovine liver mitochondria for natural polyamine uptake was verified. The presence of an MDL 72527-sensitive enzyme, with spermine oxidase activity, in the matrix of bovine liver mitochondria was determined using a kinetic approach. Western blot analysis of mitochondrial fractions and immunogold electron microscopy observations of purified mitochondria unequivocally confirmed the presence of a protein recognized by anti-spermine oxidase antibodies in the mitochondrial matrix. Preliminary kinetic characterization showed that spermine is the preferred substrate of this enzyme; lower activity was detected with spermidine and acetylated polyamines. The considerable effect of ionic strength on the Vmax/KM ratio suggested the presence of more than one negatively charged zone inside the active site cavity of this mitochondrial enzyme and this proposes that the enzyme is probably involved in the docking of positively charged substrates. These findings indicate that the mitochondrial matrix of bovine liver contains an enzyme belonging to the spermine oxidase class. Because hydrogen peroxide is generated by spermine oxidase activity, the possible involvement of the latter as an important signaling transducer under both physiological and pathological conditions should be considered. This work was done in collaboration with the Department of Molecular Sciences and Nanosystems, ‘‘Ca’ Foscari’’ University of Venice.
Addendum to abstracts presented at the 14th International Congress on Amino Acids, Peptides and Proteins
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3192067
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