Spermine Oxidase–Substrate Electrostatic Interactions: The Modulation of Enzyme Function by Neighboring Colloidal ɣ-Fe<sub>2</sub>O<sub>3</sub>
Graziano Rilievo,
Massimiliano Magro,
Federica Tonolo,
Alessandro Cecconello,
Lavinia Rutigliano,
Aura Cencini,
Simone Molinari,
Maria Luisa Di Paolo,
Cristian Fiorucci,
Marianna Nicoletta Rossi,
Manuela Cervelli,
Fabio Vianello
Affiliations
Graziano Rilievo
Department of Comparative Biomedicine and Food Science, University of Padua, Viale dell’Università 16, 35020 Legnaro, Italy
Massimiliano Magro
Department of Comparative Biomedicine and Food Science, University of Padua, Viale dell’Università 16, 35020 Legnaro, Italy
Federica Tonolo
Department of Comparative Biomedicine and Food Science, University of Padua, Viale dell’Università 16, 35020 Legnaro, Italy
Alessandro Cecconello
Department of Comparative Biomedicine and Food Science, University of Padua, Viale dell’Università 16, 35020 Legnaro, Italy
Lavinia Rutigliano
Department of Molecular Medicine, Laboratory Affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Sapienza University of Rome, Viale Regina Elena 291, 00161 Rome, Italy
Aura Cencini
Department of Comparative Biomedicine and Food Science, University of Padua, Viale dell’Università 16, 35020 Legnaro, Italy
Simone Molinari
Department of Geosciences, University of Padua, Via Gradenigo 6, 35131 Padova, Italy
Maria Luisa Di Paolo
Department of Molecular Medicine, University of Padua, Via G. Colombo 3, 35131 Padova, Italy
Cristian Fiorucci
Department of Sciences, University of Roma 3, Viale Guglielmo Marconi 446, 00146 Rome, Italy
Marianna Nicoletta Rossi
Department of Sciences, University of Roma 3, Viale Guglielmo Marconi 446, 00146 Rome, Italy
Manuela Cervelli
Department of Sciences, University of Roma 3, Viale Guglielmo Marconi 446, 00146 Rome, Italy
Fabio Vianello
Department of Comparative Biomedicine and Food Science, University of Padua, Viale dell’Università 16, 35020 Legnaro, Italy
Protein–nanoparticle hybridization can ideally lead to novel biological entities characterized by emerging properties that can sensibly differ from those of the parent components. Herein, the effect of ionic strength on the biological functions of recombinant His-tagged spermine oxidase (i.e., SMOX) was studied for the first time. Moreover, SMOX was integrated into colloidal surface active maghemite nanoparticles (SAMNs) via direct self-assembly, leading to a biologically active nano-enzyme (i.e., SAMN@SMOX). The hybrid was subjected to an in-depth chemical–physical characterization, highlighting the fact that the protein structure was perfectly preserved. The catalytic activity of the nanostructured hybrid (SAMN@SMOX) was assessed by extracting the kinetics parameters using spermine as a substrate and compared to the soluble enzyme as a function of ionic strength. The results revealed that the catalytic function was dominated by electrostatic interactions and that they were drastically modified upon hybridization with colloidal ɣ-Fe2O3. The fact that the affinity of SMOX toward spermine was significantly higher for the nanohybrid at low salinity is noteworthy. The present study supports the vision of using protein–nanoparticle conjugation as a means to modulate biological functions.
