New copper(II) hydrazone complexes with (Z)-2-(phenyl(2-(pyridin-2-yl)hydrazono)methyl)pyridine (L) were synthesized and characterized using various physicochemical methods. The geometries of the complexes can be classified as mononuclear and binuclear. The complex 1, [Cu(L)(Cl)2], is mononuclear whereas the solid-state structure of complex 2 contain a mixture of co-crystals of the mono- and binuclear complexes 2a, [Cu(L)(H2O)(SO4)], and 2b, [Cu2(L)2(μ-SO4)2]. The unit cell of 2 contains two units of the mononuclear complex 2a and one units of the binuclear complex 2b. The copper atoms contained in all the mono- and binuclear complexes are in a distorted square pyramidal geometry. The present study indicates that complexes having different nuclearities and geometries can be achieved by changing the synthetic conditions and methods. Variable temperature magnetic susceptibility measurements of the complexes have shown the presence of weak anti-ferromagnetic interactions. These interactions are mediated by intermolecular hydrogen bonding in 1 and through a symmetric sulfate bridge in 2. The EPR spectra in the polycrystalline state for 1 and 2 exhibited a broad signal at ~ 2.149 due to spin–spin interactions between two copper(II) ions. The cyclic voltammograms of complexes 1 and 2 in DMSO gave two irreversible redox waves. Density functional theory (DFT) calculations were evaluated in the study, involving the molecular specification with the use of B3LYP/LANL2DZ formalism for the copper atoms and B3LYP/6-31G for the remaining atoms. Both complexes catalyzed the dismutation of superoxide (). Furthermore, the copper complexes and the ligand were tested to explore their anticancer properties. Promising cytotoxicity of the synthesized compounds was observed against the selected cancerous cell lines of neuroblastoma, lung carcinoma, hepatocellular carcinoma and breast cancer.

The controlled release of functionally active compounds is important in a variety of applications. Here, we have synthesized, characterized, and studied the magnetic properties of three novel metal−metal-bonded tris(formamidinato) Ru2 5+ complexes. We have used different auxin-related hormones, indole-3-acetate (IAA), 2,4-dichlorophenoxyacetate (2,4-D), and 1-naphthaleneacetate (NAA), to generate [Ru2Cl(μ-DPhF)3(μ-IAA)] (RuIAA), [Ru2Cl(μ-DPhF)3(μ-2,4-D)] (Ru2,4-D), and [Ru2Cl(μ-DPhF)3(μ-NAA)] (RuNAA) (DPhF = N,N′- diphenylformamidinate). The crystal structures of RuIAA, RuIAA·THF, Ru2,4-D·CH2Cl2, and RuNAA·0.5THF have been determined by single-crystal Xray diffraction. To assess the releasing capacity of the bound hormone, we have employed a biological assay that relied on Arabidopsis thaliana plants expressing an auxin reporter gene and we demonstrate that the release of the phytohormones from RuIAA, Ru2,4-D, and RuNAA is pH- and time-dependent. These studies serve as a proof of concept showing the potential of these types of compounds as biological molecule carriers.

The catechol oxidase activity of three copper/bicompartmental salen derivatives has been studied. One mononuclear, [CuL] (1), one homometallic, [Cu2L(NO3)2] (2), and one heterometallic, [CuMnL(NO3)2] (3) complexes were obtained using the ligand H2L = N,N′-bis(3-methoxysalicylidene)-1,3-propanediamine through different synthetic methods (electrochemical, chemical and solid state reaction). The structural data indicate that the metal ion disposition models the active site of type-3 copper enzymes, such as catechol oxidase. In this way, their ability to act as functional models of the enzyme has been spectrophotometrically determined by monitorization of the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-ditert- butyl-o-benzoquinone (3,5-DTBQ). All the complexes show significant catalytic activity with ratio constants (kobs) lying in the range (223–294) × 10–4 min−1. A thorough kinetic study was carried out for complexes 2 and 3, since they show structural similarities with the catechol oxidase enzyme. The greatest catalytic activity was found for the homonuclear dicopper compound (2) with a turnover value (kcat) of (3.89 ± 0.05) × 106 h−1, which it is the higher reported to date, comparable to the enzyme itself (8.25 × 106 h−1).

RNA-binding proteins (RBPs) play a pivotal role in the lifespan of RNAs. Disfunction of RBPs are frequently the cause of cell disorders which are incompatible with life. Furthermore, the ordered assembly of RBPs and RNAs in ribonucleoprotein (RNP) particles determines the function of biological complexes, as illustrated by the survival of motor neuron (SMN) complex. Defects in SMN complex assembly causes spinal muscular atrophy (SMA), an infant invalidating disease. This multisubunit chaperone controls the assembly of small nuclear ribonucleoproteins (snRNPs), which are the critical components of the splicing machinery. However, functional and structural characterization of individual members of the SMN complex, such as SMN, Gemin3, and Gemin5, has accumulated evidence for additional roles of these proteins, unveiling their participation in other RNA-mediated events. In particular, Gemin5 is a multidomain protein that comprises WD repeat motifs at the N-terminal region, a dimerization domain at the middle region, and a non-canonical RNA-binding domain at the C-terminal end of the protein. Beyond snRNAs recognition, Gemin5 interacts with a selective group of mRNA targets in the cell environment and plays a key role in reprogramming translation depending on the RNA partner and the cellular conditions. Here we review recent studies on the SMN complex, with emphasis on the individual components regarding their involvement in cellular processes critical for cell survival

In all organisms a selected type of proteins accomplishes critical roles in cellular processes that govern gene expression. The multifunctional protein Gemin5 cooperates in translation control and ribosome binding, besides acting as the RNA-binding protein of the survival of motor neuron (SMN) complex. While these functions reside on distinct domains located at each end of the protein, the structure and function of the middle region remained unknown. Here we solved the crystal structure of an extended tetratricopeptide (TPR)-like domain in human Gemin5 that self-assembles into a previously unknown canoe-shaped dimer. We further show that the dimerization module is functional in living cells driving the interaction between the viral-induced cleavage fragment p85 and the full-length Gemin5, which anchors splicing and translation members. Disruption of the dimerization surface by a point mutation in the TPR-like domain prevents this interaction and also abrogates translation enhancement induced by p85. The characterization of this unanticipated dimerization domain provides the structural basis for a role of the middle region of Gemin5 as a central hub for protein-protein interactions