Barbara Radomska

Effects of oestradiol and oestroprogestin on erythrocyte antioxidative enzyme system activity in postmenopausal women

Objective  Data concerning the relationship between sex steroid hormones and the cellular antioxidative enzyme system are controversial. We investigated the effects of oestradiol deficiency after menopause and the influence of transdermal oestradiol therapy (ET) and hormonal (oestradiol plus medroxyprogesterone) replacement therapy (HT) on erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px) and catalase (CAT). GSH and selenium (Se) concentrations were also estimated. Serum lipid peroxide (LPO) levels were measured as an indicator of free‐radical production and lipid peroxidation.

Oxovanadium(IV) and copper(II) coordination by d-galacturonic and d-glucuronic acids

Abstract Potentiometric and spectroscopic studies show that d -galacturonic and d -glucuronic acids are effective ligands for oxovanadium(IV) ions. The carboxylate group initiates the coordination of the metal ion at pH >3 and one or two deprotonated sugar hydroxyl groups are then involved. The position of HO-4 is critical for the resulting equilibria. Cupric ions interact with ligands in a manner similar to that of oxovanadium(IV), although the stabilities of the corresponding complexes are much lower.

D-GALACTOSAMINE COMPLEXES WITH COPPER(II), NICKEL(II), AND COBALT(II)

The potentiometric and spectroscopic methods were applied to describe the equilibria for the Cu(II), Ni(II), and Co(II), D-galactosamine solutions. The stability constants, the spectral data, and the results obtained earlier precisely defined the binding ability of the aminosugars.

X-Ray evidence for the lysyl lateral amine group coordination in the (L-lysyl-L-tyrosine)Cu(II)•2H2O complex

Abstract X-ray evidence for the lysyl lateral amine group coordination to cupric ion is presented for the Cu(II) complex with L-lysyl-L-tyrosyl dipeptide. The dipeptide molecule is coordinated to the metal ion via all its functions. The α-amine, N− and COO- donors bind the metal ion forming two small chelate rings while ϵ-NH2 is coordinated to the other copper ion related by the screw axis and the polymeric complex is formed.

Potentiometric and spectroscopic studies on Cu(II) complexation to aminophosphonic acid, 1-(3-pyridyl)-1-(n-butylamino)-methanephosphonic acid

Abstract The results are reported of a potentiometric and spectroscopic study of the copper(II) complexes of aminophosphonic acid containing a pyridyl side chain. The aminophosphonic acid coordinates similarly to carboxyl amino acids, forming chelate MA and MA 2 species. Stable MAH species with only a phosphonic group coordinated to the metal ion exist at lower pH. The pyridyl side chain was found to be noneffective in the interaction with Cu(II) ion.

The unusual co-ordination ability of vasopressin-like peptides; potentiometric and spectroscopic studies of some copper(II) and nickel(II) complexes

The results are reported of a potentiometric and spectroscopic study of the H+, Cu2+, and Ni2+ complexes of [Arg8]vasopressin, [Arg8]vasotocin and some synthetic analogues containing the D-valyl residue in place of the glutamine residue at 25 °C and an ionic strength 0.10 mol dm–3(KNO3). The complexes of vasopressin and vasotocin with CuII are the most stable Cu-peptide complexes with 4N co-ordination yet reported. This results from the favourable conformation of the binding site within the ring formed by the disulphide bridge of the peptide. The high stability is lost when a non-co-ordinating residue in the ring (Gln) is replaced by a residue of opposite chirality (D–Val) as a result of steric hindrance between the α-carbon atom of the Val side chain and the neighbouring carbonyl oxygen.

Effects of mixed-ligand complex formation on deprotonation of amide groups in acid amides and peptides

The stability constants of the parent complexes of the A ligands glycinamide, glycylglycinamide, and N-acetylhistidine with copper(II), and of the mixed complexes formed with the B ligands glycine, 2,3-diaminopropionic acid, tiron, histamine, L-histidine, and 2,2′-bipyridyl, have been determined from pH-metric measurements. It has been found that glycinamide forms mixed-ligand complexes of composition [CuAB] and [CuABH–1](charges omitted), and most favourably with histamine, L-histidine, or 2,2′-bipyridyl. In the glycylglycinamide complexes of type [CuABH–1] the B ligand is co-ordinated to a considerable extent via two equatorial sites, while the bonding in the complex [CuABH–2], similarly to the other dipeptides, is mainly axial–equatorial. In the parent complexes of copper(II) with N-acetylhistidine and with N-acetylhistamine, deprotonation and co-ordination of the amide group could not be detected. It has been found, however, that the presence of B ligands containing an aromatic N donor permits deprotonation of the amide groups in both N-acetylhistidine and N-acetylhistamine.

Copper(II) complexation by 1,4-diamino-2R, 3R-butanediol and its 2R, 3S-diastereoisomer. Spectroscopic and potentiometric studies

Abstract Potentiometric and spectroscopic studies of the binding ability of two diastereoisomers of 1,4-diamino-2, 3-butanediol have shown that these amino-alcohols form very stable and specific dimeric complexes with Cu(II) involving both amino nitrogen and hydroxyl oxygen atoms. Chirality at the C(2), C(3) centres has a distinct influence on the stability of complexes formed.

Copper(II) Complexes of Tyrosine-Containing Di- and Tripeptides

Abstract Tyrosine is a constituent of many neuropeptides, and it may be assumed that it plays a fundamental role in the activity of these compounds. Recent studies on tyrosine-containing oligopeptides has established that the direct participation of the side-chain phenolate groups in metal ion binding depended considerably on the position of the tyrosine in the peptide molecule.1-5 In this note the stability constants and the binding modes of the proton and copper(II) complexes of S-tyrosyl-S-tyrosine (TyrTyr) and S-tyrosyl-S-tyrosyl-S-tyrosine (TyrTyrTyr) are presented.

Coordination of the ϵ-NH2 group of the lysyl residue in the CuTyrLys · 3H2O single crystal

Abstract The crystal and molecular structure of the violet compound ( l -tyrosyl- l -lysine)CuII · 3H2O has been determined by X-ray diffraction. The coordination mode of the peptide is the same as previously reported for the blue (LysTyr)CuII · 2H2O complex. However, the Cuα-NH2 bond distance in the violet complex is significantly shorter than that in the blue complex (1.991(7)A and 2.045(8) A respectively). The coordination number is four, not five, since there is no apically bound water molecule in the CuTyrLys complex and the aromatic ring is situated close to the basal complex plane. The considerable differences in the stereochemistry of the discussed complexes are responsible for the difference in the d—d transition energy (605 nm and 560 nm respectively).