Selected physicochemical properties of polycarboxylate cobalt(II), nickel(II), copper(II) and oxidovanadium(IV) complex compounds

Cobalt(II), nickel(II), copper(II) and oxidovanadium(IV) cations are coordination centers in many polycarboxylate complexes [1‒16]. A number of coordination compounds of transition metal ions with such ligands as polycarboxylate anions and heterocyclic organic ligands, e.g. 1,10-phenanthroline (phen) or 2,2’-bipyridine (bipy) have been examined for their biological properties [3‒16]. Their selected structures and physicochemical properties have been described in the first chapter. The polycarboxylate coordination compounds of cobalt(II), nickel(II), copper(II) and oxidovanadium(IV) have interesting antioxidant, antibacterial and antifungal activities. The antioxidant properties of polycarboxylate complexes of Co(II), Ni(II), Cu(II) and VO(IV) with 4-picoline, 1,10-phenanhroline and 2,2’-bipyridine have been investigated towards the superoxide anion radical using the nitro blue tetrazolium chloride (NBT) test and the cyclic voltammetry (CV). Their antibacterial and antifungal activities have been tested against bacteria and fungus strains that are antagonistic to the human. The determined biological properties of the oxydiacetate Co(II), Ni(II), VO(IV) complexes with bipy/phen, the thiodiacetate VO(IV) and the iminodiacetate Cu(II) complexes have been compared with these of L-ascorbic acid, which is chemical compounds commonly used as the reference antioxidant substance. Consequently, the comparison of antioxidant properties of selected cobalt( II), nickel(II), copper(II) and oxidovanadium(IV) polycarboxylate compounds is described in this work (Section 3, Tab. 1‒4). The kinetics of substitution reactions of selected copper(II) polycarboxylate complex compounds were monitored using the stopped-flow method in various reaction conditions (concentration of complex, temperature, solvent) (Rys. 5‒6) [5, 6]. The obtained results of the kinetic studies of the substitution reactions of [Cu(tda)]n with 2,2’-bipyridine in aqueous surfactants solvents: sodium dodecyl sulfate (SDSaq) and hexadecyl trimethyl- ammonium bromide (CTABaq) at 298.15 K (25 °C) are presented

Antioxidant, antibacterial and antifungal properties of complex compounds of copper(II)

Since late 1930s copper has been recognized as an essential trace metal in living organisms. Copper(II) cation plays the role as a coordination center not only in the single-nuclear complexes, but also in the multinuclear coordination compounds with a particular emphasis on the polymers as ligands. The selected complex compounds of copper(II) with ligands which are organic and inorganic species have been characterized taking into account their physico-chemical properties. In addition, the complex compounds containing ligands such as Schiff ’s bases, hydrocarbons, organic bases, and also polycarboxylic anions: oxydiacetate, thiodiacetate, iminodiacetate and dipicolinate have been described considering their role in the biological systems. Nowadays tested coordination compounds of copper(II) have interesting antibacterial activities against bacteria strains that are antagonistic to the human. The antibacterial activity of copper(II) complex is stronger than some of the known antibacterial substances e.g. ciprofloxacin. In addition, copper(II) complex compounds exhibit a 64-fold greater antimicrobial properties than copper(II) chloride. Moreover, these compounds have antifungal and antioxidant properties. The activities of antibacterial, antifungal, and antioxidant complex compounds of copper( II) have been compared to the reactivities of these compounds with complexes used as reference substances, e.g. L-ascorbic acid, in the assay using nitrotetrazolium blue

Conformational analysis of fragment of human Pin1 ww domain: influence of charged amino-acid residues on β-hairpin structure

We examined the effect of like-charged residues on the conformation of an original nine amino-acid-residue fragment of the human Pin1 WW domain (hPin1) with the following sequence: Ac-Arg-Met-Ser-Arg-Ser-Ser-Gly-Arg-Val-NH 2 (U9). This was facilitated by CD and NMR spectroscopic measurements, and molecular dynamics calculations. Our ear lier studies suggested that the presence of like-charged residues at the end of a short polypeptide chain composed of nonpolar residues could induce a chain reversal. For the U9 peptide, canonical MD simulations with NMR -derived restraints demonstrated the presence of ensembles of structures with a tendency to form a β -chain reversal. Additionally, thermal stabilities of the peptide under study were measured using differential scanning calorimetry ( DSC ). The estimated well defined phase transition point showed that conformational equilibria in the U9 peptide were strongly dependent on temperature

Critical micellar concentration and methods of its determination

Surfactants are substances, which have surface activity in aqueous solutions [1–3]. By adsorbing on the surface (boundary of phase separation) of the system, they change the surfactant properties of the liquid. Surfactants consist of a hydrophobic part (non-polar, called “tail”) and a hydrophilic part (polar, called “head”) [1–3]. The overall structure of the surfactant molecule is shown in Figure 1. In aqueous solution after exceeding one critical micellar concentration of the CMC surfatant (Critical Micelle Concentration), the surfactant molecules aggregate to form micelles [1–5]. Knowledge of CMC values and the micelle formation in solution, it determines the properties of surfactants and their subsequent use in the chemical industry. Surfactants are used in the chemical industry, inter alia, for the production of many detergents, cosmetics, paints, dyes, agrochemicals, pharmaceuticals, food or oil [2, 3]

Probing of Cu2+ ions binding to A β (5−16) peptide using ITC measurements and MD simulations

It is shown that probably three residues: His6, His14 and His16 in the original sequence A β (1−42) serve as metal-binding sites for Cu2+ions. On the other hand, there is a possibility that only one of them plays a crucial role in the formation of the{A β (1-42)-Cu2+} complex. The isothermal titration calorimetry (ITC) measurements supported by molecular dynamic simulation (MD) with the NMR-derived restrains were used to investigate the interactions of Cu2+ with A β(5-16), a fragment of the A β(1-42) protein, with the following sequence: Ac-Arg-His-Asp-Ser-Gly-Tyr-Glu-Val-His-His-Gln-Lys-NH2, termed HZ1. The conditional thermodynamic parameters suggest that the formation of the Cu2+-HZ1 complex is both an enthalpy and entropy driven process under the experimental conditions. The studies presented here (after comparison with our previous results) show that the affinity of peptides to copper metal ions depends on two factors: the primary structure (amino acid composition) and the shape of the peptide conformation adopted