The NAMI A – human ferritin system: a biophysical characterization

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.

Modification of Aβ Peptide Aggregation via Covalent Binding of a Series of Ru(III) Complexes

“…Pyridine ligand loss is not observed for the Ru-N-1 complex (Figure 1 and Figure S3), suggesting that pyridine ligand exchange is enhanced for the more bulky hydrophobic Ru-N-4 complex. The presence of the free pyridine ligand of Ru-N-4 upon incubation with Aβ 1−16 suggests further ligand exchange processes occur for this derivative in addition to DMSO exchange, similar to the reported X-ray studies (Casini et al, 2010;Messori and Merlino, 2014;Ciambellotti et al, 2018), and this difference between Ru-N-1 and Ru-N-4 may play a role in the peptide aggregation process (vide infra).…”

“…The major species formed upon incubation of HSA with the Ru-N series are His adducts at both the axial and equatorial positions following the loss of DMSO or Cl ligands (Webb et al, 2012). Interestingly, the interaction of NAMI-A with a number of proteins including lysozyme (Messori and Merlino, 2014), carbonic anhydrase (Casini et al, 2010), and human H-chain ferritin (Ciambellotti et al, 2018) has been studied by X-ray crystallography (Alessio and Messori, 2019). In these studies all of the original ligands of NAMI-A are released, and the resulting Ru(III) center is bound to the protein via His, Asp, and Glu side-chains.…”

Ferritin Nanocage: A Versatile Nanocarrier Utilized in the Field of Food, Nutrition, and Medicine

“…Therefore, ferritin nanocage has been developed into a bio-template for the encapsulation and delivery of anticancer drugs and tumor imaging agents, and applied in chemotherapy, photothermal therapy, and vivo imaging. Until now, several metallodrugs including cisplatin, carboplatin, oxaliplatin [55,122,123], Auoxo3 [92], Auoxo4, Au2phen [93], 4-PF6 [94], NAMI A [89], Ru(II)(η 6 -p-cymene) [ [96], as well as non-metallic drugs including DOX [21], curcumin [124], and cytochrome C [62], have been encapsulated in ferritin cavity to improve their bioavailability, tumor-selectivity, and cellular permeability and reduce the toxicity to normal cells. Guo and co-workers first proposed the cisplatin encapsulation and explored the cell absorption of ferritin-cisplatin nanoparticles (NPs) and their applications in tumor therapy.…”

“…The cell experiments showed that ferritin-cisplatin NPs could inhibit the growth of tumor cells slowly and continuously, and enhance the cell absorption of cisplatin [55,123]. Similar to cisplatin, alternative metal compounds based on Ru and Au have been prepared and evaluated for their cytotoxic activity in recent years, mostly by Merlino and co-workers [89,[92][93][94][95]. The adducts of these compounds with ferritin are less toxic than free drugs and are moderately selective towards cancer cells compared with non-malignant cells [80].…”

Anticancer Ruthenium(III) Complexes and Ru(III)-Containing Nanoformulations: An Update on the Mechanism of Action and Biological Activity

“…[86] These studies clearly indicated a Ru reduction in the protein complex, followed by a Ru release mechanism dependent on the reducing agent: reduction with hydrazine produced a native-like lysozyme crystal with a Raman spectrum Many preclinical studies have investigated the mechanism of action of these complexes. A large body of evidence has been gathered proving that these Ru(III) complexes are able to interact with plasma proteins-particularly with serum albumin [60][61][62][63][64] and transferrin [65][66][67][68][69]-and/or bind nucleic acids [70][71][72][73]. The extensive binding to serum proteins for KP1019 and NAMI-A was also reflected by their low distribution volume in clinical phase I evaluation [45,51].…”