Binding of tetrakis(pyrazoliumyl)porphyrin and its copper(II) and zinc(II) complexes to poly(dG-dC)2 and poly(dA-dT)2

Interactions of cationic porphyrins bearing five-membered rings at the meso position, meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin (MPzP; M is H₂, Cu^II or Zn^II), with synthetic polynucleotides poly(dG-dC)₂ and poly(dA-dT)₂ have been characterized by viscometric, visible absorption, circular dichroisim and magnetic circular dichroism spectroscopic and melting temperature measurements. Both H₂PzP and CuPzP are intercalated into poly(dG-dC)₂ and are outside-bound to the major groove of poly(dA-dT)₂, while ZnPzP is outside-bound to the minor groove of poly(dA-dT)₂ and surprisingly is intercalated into poly(dG-dC)₂. The binding constants of the porphyrin and poly(dG-dC)₂ and poly(dA-dT)₂ are on the order of 10⁶ M⁻¹ and are comparable to those of other cationic porphyrins so far reported. The process of the binding of the porphyrin to poly(dG-dC)₂ and poly(dA-dT)₂ is exothermic and enthalpically driven for H₂PzP, whereas it is endothermic and entropically driven for CuPzP and ZnPzP. These results have revealed that the kind of the central metal ion of metalloporphyrins influences the characteristics of the binding of the porphyrins to DNA.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Copper (II) and cobalt (II) complexes of chiral tetrathiafulvalene-oxazoline (TTF-OX) and tetrathiafulvalene-thiomethyl-oxazoline (TTF-SMe-OX) derivatives

Synthesis and single crystal X-ray structures of the first paramagnetic transition metal complexes containing chiral ethylenedithio-tetrathiafulvalene-oxazoline (EDT-TTF-OX) 1a-c and ethylenedithio-tetrathiafulvalene-thiomethyloxazoline 2 (EDT-TTF-(SMe)OX) ligands based on copper (II) and cobalt (II) are described. The racemic [EDT-TTF-OX][Cu(hfac)₂] complex 3a crystallizes in the triclinic centrosymmetric space group , whereas the enantiopure counterparts 3b-c crystallize in the triclinic non-centrosymmetric space group P1. Cu(II) adopts a distorted square pyramidal coordination geometry, a much weaker Cu?S_TTF interaction also being identified. The same coordination pattern around Cu(II) is observed in the complex [(rac)-EDT-TTF-(SMe)OX][Cu(hfac)₂] (4) in spite of the bidentate nature of the redox active ligand. DFT theoretical calculations afforded two equilibrium configurations for a corresponding model complex, in which the metal centre establishes secondary coordination either with one S_TTF or with the SMe group. The same ligand coordinates the cobalt (II) to afford the octahedral complex [(rac)-EDT-TTF-(SMe)OX][Co(hfac)₂] (5). In all these novel complexes, the paramagnetic centres are structurally and magnetically isolated. Cyclic voltammetry measurements show the stability of the radical cation species.     

Specific and dual antagonists of alpha(4)beta(1) and alpha(4)beta(7) integrins.

N-(3,5-Dichlorophenylsulfonyl)-(R)-thioprolyl biarylalanine 10a has been identified as a potent and specific antagonist of the alpha(4)beta(1) integrin. Altering the configuration of thioproline from R to S led to a series of dual antagonists of alpha(4)beta(1) and alpha(4)beta(7), and the N-acetyl analogue 8b was found to be the most potent dual antagonist. A binding site model for alpha(4)beta(1) and alpha(4)beta(7) is proposed to explain the structure-activity relationship.     

Synthesis and luminescence properties of a blue-emitting Sr(3.5) Y(6.5) O(2) (PO(4) )(1.5) (SiO(4) )(4.5) :Eu(2+) phosphor

A novel blue‐emitting Sr_3.5Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5:Eu²⁺ phosphor was synthesized via a solid‐state reaction. Powder X‐ray diffraction (XRD) analysis demonstrated that the Sr_3.5Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5 host had a hexagonal crystal structure in the space group P6₃/m and unit cell parameters a = 9.418 Å, c = 6.900 Å. The as‐prepared phosphor showed a blue emission and all the main emission peaks were located at around 466 nm for different excitation wavelengths of 297, 333 and 391 nm. The temperature dependence of the photoluminescence property was investigated in the range 20–250 °C, and the emission intensity decreased to 71% of the initial value at room temperature on increasing the temperature to 150 °C. According to the classical theory of fluorescent thermal quenching, the activation energy (ΔE) for the thermal quenching luminescence of the as‐prepared Sr_3.45Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5:0.05Eu²⁺ phosphor was determined to be 0.20 eV. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and properties of trinuclear polypyridyl complexes Ru(II)-Co(II)-Ru(II) and Ru(II)-Co(III)-Ru(II): Their photoinduced interconversion

The trinuclear [{Ru^II(bpy)₂(bpy-terpy)}₂Co^II]⁶⁺ complex (1⁶⁺) in which a Co(II)-bis-terpyridine-like centre is covalently linked to two Ru(II)-tris-bipyridine-like moieties by a bridging bipyridine-terpyridine ligand has been synthesised and characterised. Its electrochemical, photophysical and photochemical properties have been investigated in CH₃CN. The cyclic voltammetry exhibits two successive reversible oxidation processes, corresponding to the Co^III/Co^II and Ru^III/Ru^II redox couples at E_1/2 = −0.06 and 0.91 V vs Ag/Ag⁺ 10 mM, respectively. The one-electron oxidized form of the complex, [{Ru^II(bpy)₂(bpy-terpy)}₂Co^III]⁷⁺ (1⁷⁺) obtained after exhaustive electrolysis carried out at 0.2 V is fully stable. 1⁶⁺ and 1⁷⁺ are only poorly luminescent, indicating that the covalent linkage of the Ru(II)-tris-bipyridine centre to the cobalt subunit leads to a strong quenching of the Ru^II excited state by an intramolecular process. Luminescence lifetime experiments carried out at different temperatures indicate that the transfer is more efficient for 1⁷⁺ compare to 1⁶⁺ due to lower activation energy. Continuous irradiation of 1⁷⁺ performed at 405 nm in the presence of P(Ph)₃ acting as sacrificial electron donor leads to its quantitative reduction into 1⁶⁺, whereas similar experiment starting from 1⁶⁺ with a sulfonium salt as sacrificial electron acceptor converts 1⁶⁺ into 1⁷⁺ with a slower rate and a maximum yield of 80%. These photoinduced electron transfers were followed by UV-Visible spectroscopy and compared with those obtained with a simple mixture of both mononuclear parent complexes i.e. [Ru^II(bpy)₃]²⁺ and [Co^II(tolyl-terpy)₂]²⁺ or [Co^III(tolyl-terpy)₂]³⁺ (tolyl-terpy = 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine).     

Sericolophus (Pheronematidae) and Hernandeziana (Corythophoridae) are synonyms (Hexactinellida: Porifera)

Eight specimens of Sericolophus reflexus (Ijima) were compared with the holotype of Hernandeziana ijimae (Hernandez) to assess suspected synonymy of these taxa. An extensive morphometric analysis of the spicules available in these specimens of variable condition show that the H. ijimae holotype exhibits characters near the centre of the range of S. reflexus. It is concluded that H. ijimae is a junior synonym of S. reflexus , and that the family Corythophoridae de Laubenfels is invalid by preoccupation of its base generic name.     

Trafficking of 5-HT(3) and GABA(A) receptors (Review)

The 5-HT(3) and GABA(A) receptors are members of the Cys-loop family of neurotransmitter-gated ion channels that also include receptors for glycine and acetylcholine. The 5-HT(3) and acetylcholine receptors (cationic ion channels) and the GABA(A) and glycine receptors (anionic ion channels) generally depolarize or hyperpolarize, respectively, the neuronal membrane. Within the amino-terminal extracellular region, all members of this family exhibit a similar architecture of ligand binding domains and a number of key residues are completely conserved. The molecular characterization of their ligand binding and gating characteristics has benefited from the existence of a large repertoire of individual subunits that contribute to the pentameric ion channel. Although differences do exist, advances in our knowledge of one member offers valuable insight into the family as a whole. Each member of the Cys-loop receptors (and all other multimeric ion channels) must face the same challenges: How to assemble individual subunits into an ion channel and which subunits to use? How are assembled receptors distinguished from those that are unassembled or misassembled, then exported from the endoplasmic reticulum and delivered to the cell surface? How are they targeted to, and anchored at synaptic and extrasynaptic sites? How and when are they to be removed from these sites to provide long-term regulation of neuronal activity? In this review, we summarize our current knowledge for the 5-HT(3) and GABA(A) receptors that have provided complementary information and helped us build an overall picture of how receptor biogenesis and trafficking occurs.     

Collagen-like triple helix formation of synthetic (Pro-Pro-Gly)10 analogues: (4(S)-hydroxyprolyl-4(R)-hydroxyprolyl-Gly)10, (4(R)-hydroxyprolyl-4(R)-hydroxyprolyl-Gly)10 and (4(S)-fluoroprolyl-4(R)-fluoroprolyl-Gly)10.

For the rational design of a stable collagen triple helix according to the conventional rule that the pyrrolidine puckerings of Pro, 4-hydroxyproline (Hyp) and 4-fluoroproline (fPro) should be down at the X-position and up at the Y-position in the X-Y-Gly repeated sequence for enhancing the triple helix propensities of collagen model peptides, a series of peptides were prepared in which X- and Y-positions were altogether occupied by Hyp(R), Hyp(S), fPro(R) or fPro(S). Contrary to our presumption that inducing the X-Y residues to adopt a down-up conformation would result in an increase in the thermal stability of peptides, the triple helices of (Hyp(S)-Hyp(R)-Gly)(10) and (fPro(S)-fPro(R)-Gly)(10) were less stable than those of (Pro-Hyp(R)-Gly)(10) and (Pro-fPro(R)-Gly)(10), respectively. As reported by B?chinger's and Zagari's groups, (Hyp(R)-Hyp(R)-Gly)(10) which could have an up-up conformation unfavorable for the triple helix, formed a triple helix that has a high thermal stability close to that of (Pro-Hyp(R)-Gly)(10). These results clearly show that the empirical rule based on the conformational preference of pyrrolidine ring at each of X and Y residues should not be regarded as still valid, at least for predicting the stability of collagen models in which both X and Y residues have electronegative groups at the 4-position.     

Amidino-complexes of iron(II) and (III)

Lithioamidines {R′N(Li)C(R)NR′, I; R = CH₃, R′ = C₆H₅, p-CH₃,C₆H₄} react with iron(III) chloride

in monoglyme to produce navy-blue, high spin Fe{R′NC(R)NR′}₃ complexes which are extremely air and moisture sensitive. The corresponding reaction when R = R′ = C₆H₅ produces a soluble red complex and an air-stable green complex, whereas when R = H, R′ = C₆H₅ and R = R′ = C₆H₅ and the reaction is started at ca. ?20°, red and green complexes respectively are formed. Though all the complexes are formulated Fe{R′NC(R)NR′}₃, their properties reflect association through bridging amidino-groups. Iron(II) chloride reacts with I(R = CH₃, R′ = p-CH₃C₆H₄) to form two complexes, one crimson and soluble in organic solvents, and one brown and insoluble, which are fomulated [Fe{R′NC(R)NR′}₂]_n. The iron(III) complexes failed to react with, or were decomposed by, a variety of reducing, electrophilic and nucleophilic reagents, though blue Fe{p-CH₃C₆H₄NC(CH₃)N-p-CH₃C₆H₄}₃ reacts readily with nitric oxide to form a purple addition complex from which the N-nitroso-compound p-CH₃C₆H₄NC(CH₃)N(NO)-p-CH₃C₆H₄ was obtained in high yield. Treatment of the corresponding brown iron(II) complex with nitric oxide gave no reaction.     

Role of tfdC(I)D(I)E(I)F(I) and tfdD(II)C(II)E(II)F(II) gene modules in catabolism of 3-chlorobenzoate by Ralstonia eutropha JMP134(pJP4)

The enzymes chlorocatechol-1,2-dioxygenase, chloromuconate cycloisomerase, dienelactone hydrolase, and maleylacetate reductase allow Ralstonia eutropha JMP134(pJP4) to degrade chlorocatechols formed during growth in 2,4-dichlorophenoxyacetate or 3-chlorobenzoate (3-CB). There are two gene modules located in plasmid pJP4, tfdC(I)D(I)E(I)F(I) (module I) and tfdD(II)C(II)E(II)F(II) (module II), putatively encoding these enzymes. To assess the role of both tfd modules in the degradation of chloroaromatics, each module was cloned into the medium-copy-number plasmid vector pBBR1MCS-2 under the control of the tfdR regulatory gene. These constructs were introduced into R. eutropha JMP222 (a JMP134 derivative lacking pJP4) and Pseudomonas putida KT2442, two strains able to transform 3-CB into chlorocatechols. Specific activities in cell extracts of chlorocatechol-1,2-dioxygenase (tfdC), chloromuconate cycloisomerase (tfdD), and dienelactone hydrolase (tfdE) were 2 to 50 times higher for microorganisms containing module I compared to those containing module II. In contrast, a significantly (50-fold) higher activity of maleylacetate reductase (tfdF) was observed in cell extracts of microorganisms containing module II compared to module I. The R. eutropha JMP222 derivative containing tfdR-tfdC(I)D(I)E(I)F(I) grew four times faster in liquid cultures with 3-CB as a sole carbon and energy source than in cultures containing tfdR-tfdD(II)C(II)E(II)F(II). In the case of P. putida KT2442, only the derivative containing module I was able to grow in liquid cultures of 3-CB. These results indicate that efficient degradation of 3-CB by R. eutropha JMP134(pJP4) requires the two tfd modules such that TfdCDE is likely supplied primarily by module I, while TfdF is likely supplied by module II.     

The antiproliferative agents trans-bis(resorcylaldoximato)copper(II) and trans-bis(2,3,4-trihydroxybenzaldoximato)copper(II) and cytopathic effects of HIV

trans-Bis(resorcylaldoximato)copper(II) and trans-bis-(2,3,4-trihydroxybenzaldoximato)copper(II) (CuRES2 and CuTRI2, respectively) have been tested for antiviral properties against HIV, using an in vitro assay that measures the ability of the test compounds to prevent the killing of susceptible human cells by HIV. In the case of CuTRI2, T4 lymphocytes (CEM-V and CEM-Z cell lines) were exposed to HIV at a virus to cell ratio approx. 0.05 in microtiter plates. In the case of CuRES2, a human leukemia cell line (MT-2) was used instead. The tetrazolium salt XTT was added to all wells, and the cultures were incubated and analyzed spectrophotometrically to quantitate formazan production and viewed microscopically for detection of viable cells. In spite of their antiproliferative properties, neither agent had any detectable ability to prevent the cytopathic effects of HIV in cultures of the target cells used. Because the test system employed was constructed in such a way as to detect antiviral agents acting at any stage of the virus reproductive cycle, the results obtained strongly suggest that neither studied agent has any value as the direct prevention of the cell destruction caused by HIV is concerned.     

Induction of in vitro flowering in Dendrobium Madame Thong-In (Orchidaceae) seedlings is associated with increase in endogenous N(6)-(Delta (2)-isopentenyl)-adenine (iP) and N (6)-(Delta (2)-isopentenyl)-adenosine (iPA) levels

We analysed the endogenous cytokinin levels of Dendrobium Madame Thong-In seedlings grown in vitro during vegetative and flowering-inductive periods. HPLC was used to fractionate the extracts and radioimmunoassay (RIA) was used for assay of zeatin (Z), dihydrozeatin (DZ), N(6)-(Delta(2)-isopentenyl)-adenine (iP) and their derivatives. Coconut water used in experiments was found to contain high level (>136 pmol ml(-1)) of zeatin riboside (ZR). Protocorms and seedlings cultured in medium with coconut water were found to contain 0.5-3.9 pmol g(-1) FW of the cytokinins analysed. Seedlings (1.0-1.5 cm) cultured in flowering-inductive liquid medium containing 6-benzyladenine (BA, 4.4 muM) and coconut water (CW, 15%) contained up to 200 and 133 pmol g(-1) FW of iP and iPA, respectively. These levels were significantly higher than all other cytokinins analysed in seedlings of the same stage and were about 80- to 150-folds higher than seedlings cultured in non-inductive medium. During the transitional (vegetative to reproductive) stage, the endogenous levels of iP (178 pmol g(-1) FW) and iPA (63 pmol g(-1) FW) were also significantly higher than cytokinins in the zeatine (Z) and dihydrozeatin (DZ) families in the same seedlings. Seedlings that grew on inductive medium but remained vegetative contained lower levels of iPA. The importance of the profiles of iP and its derivatives in induction of in vitro flowering of D. Madame Thong-In is discussed.     

Linkage of plasminogen (PLG) and apolipoprotein(a) (LPA) in baboons.

Four allelic forms of serum plasminogen (PLG) were detected in baboons (Papio hamadryas Linneaus 1758) by isoelectric focusing and were determined to be inherited as autosomal codominant traits. Linkage analysis of data from 179 progeny and their parents revealed that PLG is tightly linked (lod score = 30.20) to the gene encoding apolipoprotein(a) (LPA), as in humans. No recombinant individuals were identified. This is the first linkage detected between PLG and LPA in any species other than humans and is the first genetic linkage identified in a nonhuman primate species by family studies.     

Early Devonian (~410 mya) microfossils resembling Characiopsis (Tribophyceae) and Characium (Chlorophyceae)

Unusual microfossils that occurred associated with fungal spores in the Lower Devonian (~410 mya) Windyfield chert from Scotland were composed of a narrow stipe (2.5–9 μm long) to which was attached an obovoid or elongate drop‐shaped cell up to 14 μm long; a basal attachment pad was present in several specimens. The fossils were strikingly similar morphologically to certain present‐day unicellular freshwater Tribophyceae and Chlorophyceae, but affinities to the fungal phylum Chytridiomycota also cannot be ruled out. This discovery adds to the inventory of distinctive microbial morphologies in the early non‐marine paleoecosystems.     

Acid-base and copper (II) complexation equilibria of poly(inosinic)-poly(cytidylic)

The acid-base and copper (II) complexing properties of the heteropolynucleotide poly(inosinic)-poly(cytidylic) acid were studied by means of potentiometric, spectrophotometric, CD, and molecular fluorescence titrations in a working aqueous medium of 0.15 M ionic strength at 37°C. The study of the acid-base equilibria has proved the existence of four different species in the pH interval 2–11. Two new species are detected in the presence of copper(II) ion, at acidic and neutral pH values. Spectrophotometric, CD, melting, and fluorescence data were treated with a multivariate curve resolution procedure that allowed the determination of the number of species simultaneously present in each system [acid-base equilibria, copper(II) complexation equilibria], and the estimation of their concentration profiles and of the pure spectra for each species. From the concentration profiles an unambiguous assignment of which species are present at any pH conditions can be made. Furthermore, the knowledge of the pure uv-visible, fluorescence, and CD spectra recovered by the proposed resolution method for each species brings important structural information. When this mathematical approach was applied to the thermal denaturation data, the melting profile and the uv pure spectra for all the different species or conformations formed in the melting process, were calculated. © 1997 John Wiley & Sons, Inc. Biopoly 42: 271–283, 1997     

Preparation and characterization of (9-methyladenine)triammineplatinum(II) and trans-dihydroxo(9-methyladenine)triammineplatinum(IV) complexes

The preparation is reported of [(NH₃)₃Pt(9- MeA)] X₂ (9-MeA = 9-methyladenine) with XCl (1a) and XClO₄ (1b) and of trans-[(OH)₂Pt(NH₃)₃- (9-MeA)]X₂ with XCl (2a) and XClO₄ (2b), and the crystal structure of 1b. [(NH₃)₃Pt(C₆H₇N₅)](ClO₄)₂ crystallizes in space group P2₁/n with a = 20.810(7) Å, b = 7.697(3) Å, c = 10.567(4) Å, β = 91.57(6)°, Z = 4. The structure was refined to R = 0.054, R_w = 0.063. In all four compounds Pt coordination is through N7 of 9-MeA, as is evident from ³J coupling between H8 of the adenine ring and ¹⁹⁵Pt. Pt(II) and Pt(IV) complexes can be differentiated on the basis of different ³J values, larger for Pt(II) than for Pt(IV) by a factor of 1.57 (av). In Me₂SO-d₆, hydrogen bonding occurs between Cl^? and C(8)H of 9-MeA as weil as between Cl^? and the NH₃ groups in the case of the Pt(II) complex 1a. Protonation of the 9-MeA ligands was followed using ¹H NMR spectroscopy and pK_a values for the N1 protonated 9-MeA ligands were determined in D₂O. They are 1.9 for 1a and 1.8 for 2a, which compares with 4.5 for the non-platinated 9-MeA. Possible consequences for hydrogen bonding with the complementary bases thymine or uracil are discussed briefly. Protonation of the OH groups in the Pt(IV) complexes has been shown not to occur above pH 1.     

Circular dichroism spectra of DNA quadruplexes [d(G(5)T(5))](4) as formed with G(4) and T(4) tetrads and [d(G(5)T(5)). d(A(5)C(5))]2 as formed with Watson-Crick-like (G-C)(2) and (T-A)(2) tetrads

We utilize electrophoresis and find that a thermally treated equimolar mixture of the oligonucleotide d(G(5)T(5)) and its complementary oligonucleotide d(A(5)C(5)) exhibits either two bands or a single band in one lane, depending on the conditions of the incubation solutions. The thermally treated d(G(5)T(5)) solution loaded in a different lane exhibits a single band of the parallel quadruplex [d(G(5)T(5))](4), which is composed of homocyclic hydrogen-bonded G(4) and T(4) tetrads previously proposed. For the thermally treated equimolar mixture of d(G(5)T(5)) and d(A(5)C(5)), the fast band is assigned to a Watson-Crick d(G(5)T(5)). d(A(5)C(5)) duplex, so that the slow band with the same low mobility as that of [d(G(5)T(5))](4) may be assigned to either [d(G(5)T(5))](4) itself or a [d(G(5)T(5)). d(A(5)C(5))](2) quadruplex. If the latter compound is true, this may be the antiparallel quadruplex composed of the heterocyclic hydrogen-bonded G-C-G-C and T-A-T-A tetrads proposed previously. After removing these three bands for the duplex and two kinds of hypothetical quadruplexes, we electrophoretically elute the corresponding compounds in the same electrophoresis buffer using an electroeluter. The eluted compounds are ascertained to be stable by electrophoresis. The circular dichroism (CD) and UV absorption spectra measured for the three isolated compounds are found to be clearly different. For the electrophoretic elution of the hypothetical [d(G(5)T(5))](4) quadruplex, the result of the molecularity of n = 4 obtained from the CD melting curve analysis provides further support for the formation of the parallel [d(G(5)T(5))](4) quadruplex already proposed. For the thermally treated equimolar mixture of d(G(5)T(5)) and d(C(5)A(5)), the fast band with a molecularity of n = 2 corresponds to the Watson-Crick duplex, d(G(5)T(5)). d(A(5)C(5)). The slow band with a molecularity of n = 4 indicates the antiparallel quadruplex [d(G(5)T(5)). d(A(5)C(5))](2), whose observed CD and UV spectra are different from those of [d(G(5)T(5))](4). By electrophoresis, after reannealing the eluted compound [d(G(5)T(5)). d(A(5)C(5))](2), a distinct photograph showing the band splitting of this quadruplex band into the lower duplex and upper quadruplex bands is not possible; but by a transilluminator, we occasionally observe this band splitting with the naked eye. The linear response polarizability tensor calculations for the thus determined structures of the [d(G(5)T(5))](4) quadruplex, the McGavin-like [d(G(5)T(5)). d(A(5)C(5))](2) quadruplex, and the Watson-Crick d(G(5)T(5)). d(A(5)C(5)) duplex are found to qualitatively predict the observed CD and UV spectra.     

Subunit specificity and interaction domain between GABA(A) receptor-associated protein (GABARAP) and GABA(A) receptors

GABARAP (GABA(A) receptor-associated protein) interacts with both microtubules and GABA(A) receptors in vitro and in vivo and is capable of modulating receptor channel kinetics. In this study, we use the intracellular loop of 15 GABA(A) receptor subunits to show that the interaction between GABARAP and GABA(A) receptor is specific for the gamma subunits. Pharmacological characterization of proteins purified by GABARAP affinity column indicates that native GABA(A) receptors interact with GABARAP. Quantitative yeast two-hybrid assays were used to identify the interaction domain in the gamma2 subunit for GABARAP binding, and to identify the interaction domain in GABARAP for GABA(A) receptor binding. A peptide corresponding to the GABARAP interaction domain in the gamma2 subunit was used to inhibit the interaction between GABARAP and the gamma2 subunit. In addition, the ability of GABARAP to promote cluster formation of recombinant receptors expressed in QT-6 fibroblasts was inhibited by a membrane-permeable form of this peptide in a time-dependent manner. The establishment of a model for GABARAP-induced clustering of GABA(A) receptors in living cells and the identification of subunit specificity and interaction domains in the interaction between GABARAP and GABA(A) receptors is a step in dissecting the function of GABARAP in GABA(A) receptor clustering and/or targeting.     

Dy(3+) and Mn(2+) emission in fluoride- and chloride-based Na(3) (SO(4) )X (X = F or Cl) phosphors

In the present study, Na₃(SO₄)X (X = F or Cl) halosulphate phosphors have been synthesized by the solid‐state diffusion method. The phase formation of the compounds Na₃(SO₄)F and Na₃(SO₄)Cl were confirmed by X‐ray powder diffraction (XRD) measurement. Photoluminescence (PL) excitation spectrum measurement of Na₃(SO₄)F:Ce³⁺ and Na₃(SO₄)Cl:Ce³⁺ shows this phosphor can be efficiently excited by near‐ultraviolet (UV) light and presents a dominant luminescence band centred at 341 nm for Ce³⁺, which is responsible for energy transfer to Dy³⁺and Mn²⁺ ions. The efficient Ce³⁺ → Dy³⁺ energy transfer in Na₃(SO₄)F and Na₃(SO₄)Cl under UV wavelength was observed due to ⁴ F_9/2 to ⁶H_15/2 and ⁶H_13/2 level, while Ce³⁺ → Mn²⁺ was observed due to ⁴ T₁ state to ⁶A₁. The purpose of the present study is to develop and understanding the photoluminescence properties of Ce³⁺‐, Dy³⁺‐ and Mn²⁺‐doped fluoride and chloride Na₃(SO₄)X (X = F or Cl) luminescent material, which can be the efficient phosphors in many applications, such as scintillation applications, TL dosimetry and the lamp industry, etc. Copyright © 2012 John Wiley & Sons, Ltd.