Title
The NAMI A – human ferritin system: a biophysical characterization
Author
Silvia Ciambellotti, Alessandro Pratesi, Mirko Severi, Giarita Ferraro, Enzo Alessio, Antonello Merlino, Luigi Messori
Year
2018
Journal
Dalton Transactions
Abstract
The reaction of the antimetastatic ruthenium(III) drug NAMI A with human H-chain ferritin (HuHf) was investigated through a variety of biophysical methods. We observed that the addition of HuHf to NAMI A solutions significantly increases the rate of spontaneous NAMI A hydrolysis suggesting the occurrence of a direct metallodrug–protein interaction. The resulting hydrolyzed Ru species binds the protein mostly forming a relatively tight 1 : 1 ruthenium/ferritin (subunit) adduct that was then separated and characterized. Notably, this adduct shows a characteristic CD spectrum in the visible region, which is diagnostic of the existence of at least one protein bound ruthenium center. The crystal structure of this NAMI A/HuHf adduct was subsequently solved at 1.58 Å resolution; clear evidence is given for the selective binding of a single Ru ion to His105 of each subunit with concomitant release of all other original Ru ligands in agreement with previous observations. We also noted that NAMI A produces a partial inhibition of HuHf ferroxidase activity. The implications of the above results are discussed.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Ligand binding, Visible region, Chemical stability, Inorganic chemistry, Biochemistry