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H Kozlowski

Publications and source records attributed to H Kozlowski.

At least 37 records · Page 2Linked to original sources
PubMed1993

Complexes of Cu(II) with Asn-Ser-Phe-Arg-Tyr-NH2; an example of metal ion-promoted conformational organization which results in exceptionally high complex stability.

The pentapeptide fragment of ANF, Asn-Ser-Phe-Arg-Tyr-NH2, coordinates to Cu(II) using the same four nitrogen donor centers as simple pentapeptides such as pentaalanine yet the complexes are of much higher stability as a result of a highly organized side-chain structure which is present in the complex but absent from the free ligand.

Amino Acid Sequence↗
PubMed1993

Copper(II) complexes of dipeptides containing aspartyl, glutamyl, and histidyl residues in the side chain.

Copper(II) complexes of various dipeptides containing carboxylate and imidazole-N3 donors (alpha- and gamma-GluVal, alpha- and beta-AspGly, beta-AspHis, gamma-GluHis, and homocarnosine) were studied by potentiometric and spectroscopic methods in solution. It was found that the presence of an alpha-carboxylate group in the N-terminal part of a peptide molecule significantly enhances the metal-binding ability of the ligands as a consequence of stable bis complex formation involving amino acid-like coordination. The interaction of copper(II) with beta-AspHis was characterized by the formation of an imidazole-bridged dimeric species, while the formation of bis complexes was detected in the case of gamma-GluHis. Binding of the imidazole N3 and deprotonated amide nitrogen was presumed in the copper(II)-homocarnosine system.

Aspartic Acid↗
PubMed1992

Increased LH and FSH release from the anterior pituitary of ovariectomized rat, in vivo, by copper-, nickel-, and zinc-LHRH complexes.

The effect of Cu2+, Ni2+, Zn2+ and their complexes with LHRH on the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) was estimated in in vivo experiments with the use of the method proposed by Ramirez and McCann. Ovariectomized, estradiol, and progesterone pretreated rats were injected intravenously either with LHRH alone, a metal ion alone, a mixture of metal and hormone, or a metal-LHRH complex. A metal alone or a mixture of it with LHRH did not affect gonadotropin release at all or no more than LHRH alone. However, the complex of Cu2+ with LHRH brought about a high release of LH and even higher release of FSH. This indicates that copper complex is more effective than metal-free LHRH. The nickel complex showed a similar although lesser effect. The zinc complex had similar potency to free LHRH though higher FSH-releasing ability was noticed. We conclude that copper-, nickel-, and zinc-LHRH complexes were more potent than the peptide hormone itself and promoted the FSH release in the ovariectomized, estradiol, and progesterone pretreated rats.

Animals↗
PubMed1992

Potentiometric and spectroscopic studies of the Cu(II) complexes of Ala-Arg8-vasopressin and oxytocin: two vasopressin-like peptides.

The results are reported of a potentiometric and spectroscopic study of the H+ and Cu2+ complexes of Ala-Arg8-vasopressin (Ala-AVP) and oxytocin at 25 degrees C and an ionic strength of 0.10 mol dm-3 (KNO3). The coordination chemistry of oxytocin and Cu(II) has been shown to be virtually identical to that of Arg8-vasotocin, forming unusually stable complexes with four nitrogen coordination (4N complexes) below pH 7. Spectroscopic evidence suggests weak interaction between Cu(II) and the sulphur atom of the -Cys6- residue in the 2N species (pH congruent to 6) but this is absent in the 4N complex. Evidence is also presented for perturbation of electronic transitions within the aromatic ring of the Tyr residue by Cu(II). While the physiological potency of Ala-AVP is very high, its coordination chemistry differs significantly from that of Arg8-vasopressin. With Cu(II) it forms complexes of similar stability to those with tetraglycine, demonstrating that the addition of an alanyl residue to the amino-terminal of the peptide destroys the conformation which is particularly favorable for rapid 4N coordination.

Amino Acid Sequence↗
PubMed1992

The coordination of copper(II) to 1-hydroxy-4-(glycyl-histidyl-lysine)-anthraquinone; a synthetic model of anthraquinone anti-cancer drugs.

Results are reported of a pH-metric and spectroscopic (CD and ESR) study of the complexes formed between the pseudo-peptide 1-hydroxy-4-(Gly-His-Lys)-anthraquinone (Q-GHK) since, when complexed to copper ions, Q-GHK has been shown to be very effective in promoting the formation of free radicals and inducing DNA cleavage. Q-GHK forms very stable complexes with copper, the major species being bonded to three nitrogen donors in the coordination plane: an imidazole-N of the His residue and the peptide nitrogens of the Gly and His residues. This species is probably stabilized through bonding of the fourth planar coordination site of Cu(II) to the 9-anthraquinone oxygen. At high Q-GHK:copper ratios a second Q-GHK molecule is coordinated through its imidazole-N donor.

Anthraquinones↗
PubMed1991

A potentiometric and spectroscopic study of the proton, and copper (II) and zinc (II) complexes formed by fibrinopeptide A.

Results are reported for a potentiometric and spectroscopic (visible, CD, and EPR) study of the complexes of fibrinopeptide A (Ala-Asp-Ser-Gly-Glu-Gly-Asp-Phe-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg) with H+, Cu2+ and Zn2+. They show that the peptide forms stable complexes with Cu2+, largely as a result of the Asp2 residue, and that its coordination behavior is almost identical to that of the N-terminal tetrapeptide fragment, Ala-Asp-Ser-Gly. Hence the influence of the remaining amino acid residues on coordination to Cu2+ is insignificant.

Amino Acid Sequence↗
PubMed1990

The unusual behavior of the inhibitor S(+)(1-amino-2-phenylethyl)phosphonic acid towards carboxypeptidase A.

The molecular (1-Amino-2-phenylethyl)phosphonic acid is shown to inhibit the enzymatic activity of carboxypeptidase A. Through the spectroscopic investigation of the cobalt(II) substituted enzyme we propose that it binds the enzyme in the 1:1 ratio directly at the metal, probably through the phosphate group like phosphate itself. The aromatic group is proposed to sit in the so-called S1 hydrophobic pocket. This is a unique behavior among the inhibitors of the enzyme. The S'1 site is still available in the binary adduct so that a ternary complex can be obtained with molecules like L-Phenylalanine, which enter that site.

Animals↗
PubMed1990

Metal binding ability of hypermodified nucleosides of t-RNA. Potentiometric and spectroscopic studies on the metal complexes of N-[(9-beta-D-ribofuranosylpurin-6-yl)-carbamoyl] threonine.

Copper(II), nickel(II), zinc(II), manganese(II), and magnesium(II) complexes of t6A (N-[9-beta-D-ribofuranosylpurin-6-yl)carbamoyl] threonine and t6Ade (N6(threoninocarbonyl)adenine) were studied by potentiometric and spectroscopic methods. It was found that t6Ade has three dissociable protons in the accessible pH range (N1 and N9 of purine and carboxylate), while only two pK values are characteristic of t6A. Magnesium(II) and manganese(II) do not interact effectively with these ligands, but copper(II) and nickel(II) ions form very stable complexes with the coordination of purine N1, deprotonated amide nitrogen, and carboxylate oxygen donors.

Adenosine↗
PubMed1990

Transition metal complexes of L-cysteine containing di- and tripeptides.

Nickel(II), cobalt(II), zinc(II), and cadmium(II) complexes of Ala-Cys, Phe-Cys, and Ala-Ala-Cys were studied by potentiometric and spectroscopic methods. Ni(II) induces deprotonation and coordination of the amide nitrogens, and the stable monomeric or oligomeric complexes are formed, depending on the metal to ligand molar ratios. Formation of the stable bis-complexes with [S,O] coordination mode is characteristic for cobalt(II), zinc(II), and cadmium(II) ions.

Amino Acid Sequence↗
PubMed1989

In vitro interaction of mutagenic chromium (VI) with red blood cells.

The interaction of mutagenic Cr(VI) with red blood cells has been studied by ESR spectroscopy. Signals of two Cr(V) species are observed almost immediately after contacting red cells with chromate(VI) aqueous solution at pH 7.4. The signal at go = 1.985, which decays within one hour, is attributed to a Cr(V) complex formed by glutathione due its reducing and chelating ability. The other signal at go = 1.979, which is distinctly more persistent, may indicate that some immobilization of the formed Cr(V) ions takes place on the macromolecular cell components, e.g. glycoproteins.

Adult↗
PubMed1989

LHRH interaction with Zn(II) ions.

Luteinizing hormone-releasing hormone (LHRH), a hypothalamic neurohormone, forms a complex with Zn ions in solution. In order to explain the structure of this complex, the stability constants of Zn(II) complexes of LHRH and also pyroglutamyl-histidine-methylester, N-acetyl-histamine, and N-acetyl-histidine were established with the use of potentiometric technique. The nuclear magnetic resonance spectroscopy shows that the mode of coordination of Zn(II) to LHRH consists of binding to the imidazole nitrogen and the peptide oxygen of the His-Trp bond.

Chemical Phenomena↗
PubMed1988

Metal complexes of luteinizing hormone-releasing hormone (LHRH). potentiometric and spectroscopic studies.

The results are reported of a potentiometric and spectroscopic study of the H+, Cu2+, and Ni2+ complexes of luteinizing hormone-releasing hormone (LHRH, HL) at 25 degrees C and an ionic strength 0.10 mol dm-3 (KNO3), since there is much evidence that the in vivo release of LHRH is influenced by the concentration of copper ions. With Cu2+ the hormone has been shown to behave similarly to the thyrotropin releasing factor, forming a very stable [CuH-1L] complex involving coordination of three nitrogen donors: the Nim atom of the imidazole side chain and the two amido-N atoms of the pyroglutamylhistidyl unit. With Ni2+, coordination proceeds differently to give four nitrogen coordination.

Circular Dichroism↗
PubMed1988

Metal ion-tetracycline interactions in biological fluids. Part 8. Potentiometric and spectroscopic studies on the formation of Ca(II) and Mg(II) complexes with 4-dedimethylamino-tetracycline and 6-desoxy-6-demethyl-tetracycline.

Effects of metal ion-tetracycline (TC) interactions on both gastrointestinal absorption and pharmacological activity of these drugs are well documented. In particular, recent simulation studies based on newly determined complex stability constants have drawn attention to the potential influence of Ca2+ and Mg2+ ions on the bioavailability of various TC derivatives in blood plasma. Contrary to previous thoughts, it was demonstrated in these studies that the fraction of antibiotic not bound to proteins almost exclusively occurs as calcium and magnesium complexes. Among this fraction, predominant binuclear species are electrically charged, and as such cannot passively diffuse through cell membranes. It was thus postulated that the partial blocking of one of the potential coordination sites of the TC molecule, which would favor the formation of neutral mononuclear complexes, should result in a better tissue penetration of the drug. Such correlations were recently established for specific derivatives. Before possible modifications of the TC molecule can be envisaged, it is necessary that all the chelating sites involved in the relevant complexes be properly assigned. As tetracyclines are very complex ligands, the present paper first deals with the coordination of calcium and magnesium with two simpler parent substances, i.e., 4-dedimethylamino-tetracycline (DTC) and 6-desoxy-6-demethyl-tetracycline (DSC). After the quantitative investigation of the proton and metal complex equilibria involved, UV and circular dichroism spectroscopies are used to study the corresponding structural aspects. In DTC complexes, the BCD ring system acts as the exclusive coordination site for both metals. For DSC, however, the N4 atom plays a leading role in the metal binding and would be the only donor involved in 1:1 species; in ML2 complexes, the second ligand is thought to bind through the BCD ring system.

Calcium↗
PubMed1987

The influence of subcutaneously administered lead(II) acetate on the concentrations of copper, iron, and zinc in the blood, kidney, liver, and spleen of rats.

The concentrations of copper, iron, lead, and zinc in the blood, kidney, liver and spleen were determined before and after subcutaneous administration of lead(II) acetate (100 mg Pb kg-1 body weight) to male albino Wistar rats. The control rats had the following concentrations (microgram g-1 dry weight) of Cu, Fe, Pb and Zn: blood, 4.5, 3200, 2.1, 182; kidney, 36, 585, 120, 92; liver, 11.1, 720, 14.3, 124; spleen, 4.5, 420, 7.0, 76. After administration of lead, rats were sacrificed after 12, 24, 48, 72 and 96 h. The Pb concentration in the blood remained constant for the first 24 h at the level of the control group (2.1 micrograms g-1) and had decreased to half that level at 96 h. The lead concentrations peaked in the organs at 110-142% of those in the control group and had decreased at 96 h to levels considerably below those in the control group. The concentrations of Cu, Fe and Zn increased in the three organs to values 117-161% found for the control group. At 96 h the concentrations of Cu, Fe and Zn in the spleen had returned to levels of the control group; the concentrations in the liver were 112-153%, and in the blood 89-93% of those of the control group. In the kidney the iron (110%) and the zinc (126%) concentrations at 96 h were higher than the control values, whereas the copper concentration was the same as the control value. The concentrations in the blood were least affected. The most drastic changes were observed in the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

[Histological, morphometric and topochemical analysis of placentas from pregnancies with EPH Gestosis (author's transl)].

The authors' studies have shown three pathological phenomena to be predominant in placentas of women with EPH gestosis: disappearance of acid mucosubstance from wall of spiral arteries, reduction of ATPase, 5-Nase, and aP activities on apical and basal surfaces of terminal villi, and numerical increase as well as de-differentiation of trophoblastic nodes. Vulnerability of vascular walls to the action of vasodepressive factors is aggravated, according to the authors, in cases of complicated gestosis in which aMPS levels in the muscular membranes of spiral arteries are inadequate.

Adenosine Triphosphatases↗
PubMed1978

Stages of the development of immunologic response in regional lymph nodes draining breast cancer.

During the studies of regional lymph nodes originating from 50 patients with breast cancer, there were distinguished four stages in development of immune response. The first, stage of induction of the response concerned patients with non-infiltrating carcinoma. The second stage of the active immune response was observed in 1/3 of the patients with infiltrating cancer without metastases. In these cases, in the pattern of regional lymph nodes predominated medium sized lymphocytes within the thymus-dependent inner cortex, while in outer areas there was an increased number of small active follicles. Within the sinusoidal structures there predominated proliferating prohistiocytes growing in interaction with small lymphocytes. The third stage of immune response was characterized by weak activity and progressive cortical strophy of the lymph nodes and it was observed in 2/3 of the patients with invasive cancer. The fourth stage of immunologic response concerned the patients with minute-metastases within the regional lymph nodes. In these cases one group of the lymph nodes showed unstimulated pattern while the other a highly stimulated pattern with the presence of giant follicles.

Adult↗
PubMed1977

Stages of development of immunologic response in the regional lymph nodes in invasive cancer of the uterine cervix.

In a review of histologic sections of regional lymph nodes removed during surgery in the course of invasive cancer of the uterine cervix from 84 patients there have been distinguished four basic stages of immunologic response. Active immune response (I and II stage) was detected in all patients with non-metastatic cancer and minimal stromal invasion and 41% of patients with advanced invasion. The regional lymph nodes, in these cases, exhibited increased number of small primary or secondary lymph follicles, proliferative sinus histiocytosis and expanded thymus--dependent inner cortex. In 59% of the patients with invasive cancer but without metastases the regional lymph nodes showed weak reactive capacities (III stage). In cases with minimal metastases the immune response was dissociated (IV stage). One group of lymph nodes showed an unstimulated pattern and others a high stimulated pattern.

Acid Phosphatase↗