Chloride Adducts Research Articles

PapA3 Is an Acyltransferase Required for Polyacyltrehalose Biosynthesis in Mycobacterium tuberculosis

Mycobacterium tuberculosis possesses an unusual cell wall that is replete with virulence-enhancing lipids. One cell wall molecule unique to pathogenic M. tuberculosis is polyacyltrehalose (PAT), a pentaacylated, trehalose-based glycolipid. Little is known about the biosynthesis of PAT, although its biosynthetic gene cluster has been identified and found to resemble that of the better studied M. tuberculosis cell wall component sulfolipid-1. In this study, we sought to elucidate the function of papA3, a gene from the PAT locus encoding a putative acyltransferase. To determine whether PapA3 participates in PAT assembly, we expressed the protein heterologously and evaluated its acyltransferase activity in vitro. The purified enzyme catalyzed the sequential esterification of trehalose with two palmitoyl groups, generating a diacylated product similar to the 2,3-diacyltrehalose glycolipids of M. tuberculosis. Notably, PapA3 was selective for trehalose; no activity was observed with other structurally related disaccharides. Disruption of the papA3 gene from M. tuberculosis resulted in the loss of PAT from bacterial lipid extracts. Complementation of the mutant strain restored PAT production, demonstrating that PapA3 is essential for the biosynthesis of this glycolipid in vivo. Furthermore, we determined that the PAT biosynthetic machinery has no cross-talk with that for sulfolipid-1 despite their related structures.

Reactive desorption electrospray ionization mass spectrometry (DESI-MS) of natural products of a marine alga.

Presented here is the optimization and development of a desorption electrospray ionization mass spectrometry (DESI-MS) method for detecting natural products on tissue surfaces. Bromophycolides are algal diterpene-benzoate macrolide natural products that have been shown to inhibit growth of the marine fungal pathogen Lindra thalassiae. As such, they have been implicated in antimicrobial chemical defense. However, the defense mechanisms are not yet completely understood. Precise detection of these compounds on algal tissue surfaces under ambient conditions without any disruptive sample processing could shed more light onto the processes involved in chemical defense of marine organisms. Conventional DESI-MS directly on algal tissue showed relatively low sensitivity for bromophycolide detection. Sensitivity was greatly improved by the addition of various anions including Cl(-), Br(-), and CF(3)COO(-) into the DESI spray solvent. Chloride adduction gave the highest sensitivity for all assayed anions. Density functional optimization of the bromophycolide anionic complexes produced during DESI supported this observation by showing that the chloride complex has the most favorable binding energy. Optimized DESI protocols allowed the direct and unambiguous detection of bromophycolides, including A, B, and E, from the surface of untreated algal tissue.

A Coordination Polymer of Bis-[2-(dimethylamino)ethanolato]dimethylsilane with a Lithium Chloride Dimer

The reaction of lithium 2-(dimethylamino)ethanolate with Me2SiCl2 yielded a lithium chloride adduct of Me2Si- (OCH2CH2NMe2)2. Despite the application of an excess of Me2SiCl2, the formation of ClMe2SiOCH2CH2NMe2 was not observed. [Me2Si(OCH2CH2NMe2)2・Li2Cl2] was characterised by NMR spectroscopy and determination of its crystal structure by X-ray diffraction. In the solid state it forms endless chains consisting of Li2Cl2 rhombi, with the lithium atoms chelated by the O and N atom of one OCH2- CH2NMe2 substituent of Me2Si(OCH2CH2NMe2)2 units.

Phosphatidic Acid and N-Acylphosphatidylethanolamine Form Membrane Domains in Escherichia coli Mutant Lacking Cardiolipin and Phosphatidylglycerol

The pgsA null Escherichia coli strain, UE54, lacks the major anionic phospholipids phosphatidylglycerol and cardiolipin. Despite these alterations the strain exhibits relatively normal cell division. Analysis of the UE54 phospholipids using negativeion electrospray ionization mass spectrometry resulted in identification of a new anionic phospholipid, N-acylphosphatidylethanolamine. Staining with the fluorescent dye 10-N-nonyl acridine orange revealed anionic phospholipid membrane domains at the septal and polar regions. Making UE54 null in minCDE resulted in budding off of minicells from polar domains. Analysis of lipid composition by mass spectrometry revealed that minicells relative to parent cells were significantly enriched in phosphatidic acid and N-acylphosphatidylethanolamine. Thus despite the absence of cardiolipin, which forms membrane domains at the cell pole and division sites in wild-type cells, the mutant cells still maintain polar/septal localization of anionic phospholipids. These three anionic phospholipids share common physical properties that favor polar/septal domain formation. The findings support the proposed role for anionic phospholipids in organizing amphitropic cell division proteins at specific sites on the membrane surface.

The Formation of Isomorphous Packing Structures in Complexes of Dodecyltrimethylammonium Halides Complexes with Rac-1,1′-Bi-2-naphthol

The crystal and molecular structures of 1:1 complexes of dodecyltrimethylammonium bromide and chloride adducts of rac-1,1′-Bi-2-naphthol (hereafter, 12TAB/BNP and 12TAC/BNP) have been determined by X-ray diffraction techniques. The crystal data and crystal structures revealed that the complexes crystallize in monoclinic crystal system with space group (P21/a) and Z-value (4), and also exhibit isomorphous packing structure. The crystal complexes are stabilized by electrostatic interactions, hydrogen bonds, and C–H…π interactions. The different lattice parameters as well as the different sizes of the halide ions (Br− and Cl−) do not prevent both complexes (12TAB/BNP and 12TAC/BNP) from crystallizing with similar packing as well as common hydrogen bonding network and non-bonded interactions. Thus, the entering or leaving groups (Br−/Cl−) do not alter the existing hydrogen bonding and any other non-bonded interactions and thereby effects isomorphous packing structure.

Polyfluorophenylamino Germanes and Their Titanium (IV) Chloride Adducts

Disproportionation reactions between (CF 3 CH 2 O) 3 GeNHC 6 H 5 − n F n and TiCl 4 in petroleum ether (40−60°C) at 0° to −10°C give (CF 3 CH 2 O) 2 Ge(NHC 6 H 5 − n F n ) 2 .2TiCl 4 and (CF 3 CH 2 O)Ge(NHC 6 H 5 − n F n ) 3 . 2TiCl 4 adducts. However, complete disproportionation of (CF 3 CH 2 O) 3 Ge(NHC 6 H 5 − n F n ) (n = 1,2) occurs at −55 to −60°C to give Ge(NHC 6 H 5 − n F n ) 4 .3TiCl 4 . These complexes give double adducts on reactions with CH 3 NO 2 and CH 3 CN. All the products are characterized by elemental analyses and IR, 1 H, and 19 F NMR spectroscopy. A comparative disproportionation of the germanamines and analogous silanamines is discussed.

MALDI Linear-Field Reflectron TOF Post-Source Decay Analysis of Underivatized Oligosaccharides: Determination of Glycosidic Linkages and Anomeric Configurations Using Anion Attachment

Six different anionic species (fluoride, chloride, bromide, iodide, nitrate, and acetate) are tested for their abilities to form anionic adducts with neutral oligosaccharides that are detectable by MALDI-TOF mass spectrometry. Fluoride and acetate cannot form anionic adducts with the oligosaccharides in significant yields. However, bromide, iodide, and nitrate anionic adducts consistently appear in higher abundances relative to [M - H](-), just like the highly stable chloride adducts. Post-source decay (PSD) decompositions of Br(-), I(-), and NO(3)(-) adducts of oligosaccharides provide no structural information, i.e., they yield the respective anions as the main product ions. However, determination of linkage types is achieved by analysis of structurally-informative diagnostic peaks offered by negative ion PSD spectra of chloride adducts of oligosaccharides, whereas the relative peak intensities of pairs of diagnostic fragment ions allow differentiation of anomeric configurations of glycosidic bonds. Thus, simultaneous identification of the linkage types and anomeric configurations of glycosidic bonds is achieved. Our data indicate that negative ion PSD fragmentation patterns of chloride adducts of oligosaccharides are mainly determined by the linkage types. Correlation may exist between the linkage positions and fragmentation mechanisms and/or steric requirements for both cross-ring and glycosidic bond fragmentations. PSD of the chloride adducts of saccharides containing a terminal Glcalpha1-2Fru linkage also yields chlorine-containing fragment ions which appear to be specifically diagnostic for a fructose linked at the 2-position on the reducing end. This also allows differentiation from saccharides with a 1-1 linked pyranose on the same position.

C6N7H3O3·H2N(CH3)2Cl·H2O – a Dimethylammonium Chloride Adduct of Cyameluric Acid – Synthesis, Structure and Properties

AbstractThe dimethylammonium chloride adduct hydrate of cyameluric acid was obtained by slow hydrolytic decomposition of cyameluric chloride C6N7Cl3 dissolved in N,N‐dimethylformamide. Single crystals of C6N7H3O3·H2N(CH3)2Cl·H2O have been obtained after evaporation of the solvent. The structure has been determined by single‐crystal XRD (P 21/c, a = 6.0908(12), b = 22.710(5), c = 9.821(2) Å, β = 105.63(3)°, V = 1308.2(5) Å3, Z = 4, T = 130 K). In the solid, only the all‐keto tautomere of cyameluric acid occurs. The molecular entities are interconnected by an extensive hydrogen bonding network. Vibrational and thermal properties of the compound have been investigated.

Synthesis and NHC Lability of d0 Lithium, Yttrium, Titanium, and Zirconium Amido Bis(N-heterocyclic carbene) Complexes

The synthesis of lithium(I) complexes of the neutral and anionic salts of a tridentate aminobis(N-heterocyclic carbene) ligand, L, are reported (L = N{CH2CH2(1-C[NCHCHNMes])}2), along with the X-ray diffraction determined molecular structure of the imidazolium proligand [H2N{CH2CH2(1-HC[NCHCHNMes])}2][Br]3 (H4LBr3). The transamination reaction between the lithium chloride adduct of HL and Y[N{SiMe3}2]3 affords yttrium amidocarbene complexes, while the transamination reaction between the imidazolium proligand and Ti(NMe2)4 or Zr(NMe2)4 affords a titanium or zirconium amidocarbene complex, respectively. The molecular structure of one of the yttrium products, Y(L)(N{SiMe3}2)Cl, is reported. The reactivity of a selection of the complexes with phosphine oxides is compared.

A triphenylmethanol–pyridinium chloride (1/1) adduct containing a one-dimensional ionic substructure

The title compound, (C6H5)3COH·C5H6N+·Cl−, was surprisingly obtained as a precipitate during the dissolution (and unexpected hydrolysis reaction) of chloro­triphenyl­methane with a recently opened `silylation-grade' bottle of pyridine. A one-dimensional pyridinium chloride substructure is observed in the crystal structure which exhibits hydrogen bonding between the pyridinium cation and the chloride anion. The donation of the hydroxyl hydrogen to the chloride ion produces a hydrogen-bonding inter­action that links the triphenyl­methanol mol­ecules to this substructure. The aromatic rings are not involved in stacking inter­actions.

Distortion Isomerism of Cu(II) Chloride Adducts with Bis(2-benzimidazolyl)ethane. Synthesis, Characterization, X-ray Structures and Spectroscopy of Four Different Isomers

3D structures and spectroscopic properties are reported of four compounds with the ligand bis(2-benzimidazolyl)ethane (hereafter abbreviated as dbz) attached to CuCl2, all having the general formula [Cu(dbz)Cl2](Hb) x . (in which Hb = EtOH or MeOH and x = 1/2 or 1). The X-ray crystal structure has been solved from these four slightly different compounds, namely: green α-[CuCl2dbz](C2H5OH)1/2 (1), the red compound β-[CuCl2dbz](C2H5OH)1/2 (2), which both have two slightly different units in the unit cell, the red α-[CuCl2dbz](CH3OH) (3) and a blue–green compound β-[CuCl2dbz](CH3OH) (4). The geometry around the Cu(II) anion is distorted tetrahedral for all four compounds, with chromophores consisting of two nitrogen atoms of the bidentate chelating dbz molecule and two chloride anions. The unit cells of compound 1 and 2 consist of two chemically identical, but crystallographically different units, while compounds 3 and 4 each have only one independent CuCl2-(dbz) unit. The major differences are observed in the dihedral angles NCuN–ClCuCl, which vary from 29.3 to 77.1° for the four compounds. The differences are related to different packing effects, ring–ring stacking and H-bond interaction, due to the two different alcohols used. In fact these four compounds represent a new range of examples of distortion isomerism in pseudo-tetrahedrally coordinated species. Characterisation of the four compounds has been completed by IR, EPR and LF spectroscopy.

Analysis of Sugars and Sugar Polyols in Atmospheric Aerosols by Chloride Attachment in Liquid Chromatography/Negative Ion Electrospray Mass Spectrometry

Sugars and sugar polyols are relatively abundant groups of water-soluble constituents in atmospheric aerosols. This paper describes a method that uses liquid chromatography-mass spectrometry (LC-MS) to analyze sugars and sugar polyols in atmospheric aerosols, ranging from C3 sugar alcohols to trisaccharides. Postcolumn addition of chloroform in acetonitrile was found to greatly enhance ionization of these compounds by forming chloride adduct ions in the negative-ion mode using electrospray ionization. A gradient elution program starting at 5%:95% H20/acetonitrile and ending at 30%:70% H2O/acetonitrile provides baseline separations of the sugars and sugar polyols on an amino-based carbohydrate column. The detection limits based on quantification of [M + 35Cl]- adduct ions were in the order of 0.1 microM. By eliminating the need for derivatization, this LC-MS based method provides a simpler alternative method to the commonly used and more laborious gas-chromatography based methods. It also has an additional advantage of being able to quantify trisaccharide sugars. The method was applied to analyze 30 ambient samples of fine particulate matter collected at a site away from urban centers in Hong Kong. The sugar compounds positively identified and detected in the ambient samples included four sugar alcohols (glycerol, erythritol, xylitol, and mannitol), three monosacchride sugars (xylose, fructose, and glucose), two disaccharides (sucrose, trehalose), two trisaccharides (melezitose, raffinose), and one anhydrosugar (levoglucosan). The sum of these sugar and sugar polyol compounds ranged from 38 to 1316 ng m(-3), accounting for an average of 1.3% organic carbon mass. Through the use of a principal component analysis of the ambient measurements, the mono- to trisactharide sugars and C3-C5 sugar polyols were identified to be mainly associated with soil/soil microbiota while the anhydrosugar (levoglucosan) was associated with biomass burning.

Gold(i) chloride adducts of 1,3-bis(di-2-pyridylphosphino)propane: synthesis, structural studies and antitumour activity

The novel water soluble bidentate phosphine ligand 1,3-bis(di-2-pyridylphosphino)propane (d2pypp) has been synthesized by a convenient route involving treatment of 2-pyridyllithium with Cl(2)P(CH(2))(3)PCl(2) and isolation in crystalline form as the hydrochloride salt. The synthesis of the precursor Cl(2)P(CH(2))(3)PCl(2) has been optimized by the use of triphosgene as the chlorinating agent. The 2 : 1 and 1 : 2 AuCl : d2pypp adducts have been synthesized and characterized by NMR spectroscopy and single crystal X-ray studies, and shown to be of the form (AuCl)(2)(mu-d2pypp-P,P') and [Au(d2pypp-P,P')(2)]Cl(.3.75H(2)O), respectively. The latter is more lipophilic than analogous 1 : 2 adducts of gold(I) chloride with the diphosphine ligands 1,2-bis(di-n-pyridylphosphino)ethane (dnpype) for n = 2, 3 and 4, based on measurement of the n-octanol-water partition coefficient (log P = -0.46). A single crystal structure determination of the 1 : 2 Au(I) complex of the 3-pyridyl ethane ligand shows it to be of the form [Au(d3pype-P,P')(2)]Cl.5H(2)O. The in vitro cytotoxic activity of [Au(d2pypp)(2)]Cl was assessed in human normal and cancer breast cells and selective toxicity to the cancer cells found. The significance of these results to the antitumour properties of chelated 1 : 2 Au(I) diphosphine complexes is discussed.

Detection of explosives on skin using ambient ionization mass spectrometry

Single nanogram amounts of the explosives TNT, RDX, HMX, PETN and their mixtures were detected and identified in a few seconds on the surface of human skin without any sample preparation by desorption electrospray ionization (DESI) using a spray solution of methanol-water doped with sodium chloride to form the chloride adducts with RDX, HMX, and PETN while TNT was examined as the radical anion and tandem mass spectrometry was used to confirm the identifications.

Tandem mass spectra of divalent metal ion adducts of glycosyl sulfides, sulfoxides and sulfones; distinction among stereoisomers

The tandem mass spectra of the divalent metal ion (Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Ni2+, Co2+ and Zn2+) adducts of acetylated 1,2-trans-glycosyl sulfides, sulfoxides and sulfones were examined using low energy collision-induced dissociation on a Quattro II quadrupole tandem mass spectrometer. Abundant doubly charged ions, such as [3M + Met]2+ and [2M + Met]2+, were observed with alkaline earth metal chlorides. The other ions observed were [M + MetCl]+, [M + MetOAc]+, [M + MetO2SPh]+ and [2M + MetCl]+. The deprotonated metal adducts [M + Met-H]+ were seen only in the sulfones. The divalent metal ion adducts showed characteristic fragmentation pathways for the glycosyl sulfides, sulfoxides and sulfones, depending on the site of metal attachment. The doubly charged metal ion adducts dissociate to two singly charged ions, [M + MetOAc]+ and [M - OAc]+, in the sulfides and sulfoxides. In the sulfones, the adducts dissociate to [M + MetO2SPh]+ and [M - O2SPh]+. In contrast to the alkaline earth metals, which attach to the acetoxy functions, the transition metals attach to the sulfide and sulfoxide functions. The metal chloride adducts display characteristic fragmentation for the sulfides, sulfoxides and sulfones. The glucosyl, mannosyl and galactosyl sulfides, sulfoxides and sulfones could be differentiated on the basis of the stereochemically controlled MS/MS fragmentations of the metal chloride adducts.

Living Cationic Polymerization of a Novel Bicyclic Conjugated Diene Monomer, Tetrahydroindene, and Its Block Copolymers with Vinyl Ether

The living cationic polymerization of a novel bicyclic conjugated diene monomer, tetrahydroindene (THI) (bicyclo[4.3.0]-2,9-nonadiene), was achieved using the SnCl4-based initiating system, in which the Lewis acid works as an activator for the dormant C−Cl terminal originating from the hydrogen chloride adduct of the 2-chloroethyl vinyl ether as an initiator (1) in the presence of a nucleophilic additive such as ethyl acetate. The number-average molecular weights of the obtained polymers increased in direct proportion to the monomer conversion, and the MWDs were narrow throughout the reactions (Mw/Mn ∼ 1.2). The well-defined terminal structure of the obtained poly(THI) was confirmed by the 1H NMR and MALDI-TOF MS analysis, which shows the presence of the initiator moiety at the α end and the chlorine at the ω end. The living cationic block copolymerization of isobutyl vinyl ether (IBVE) followed by THI led to the di- and triblock copolymers consisting of the hard nonpolar THI and soft polar IBVE segments ...

Polyfluorophenylaminosilane–Titanium (IV) Chloride Adducts

Si(NHC6H5-nFn)4.xTiCl4 [n = 2–5; x = 3,4] are obtained from the disproportionation reactions between (CF3CH2O)3SiNHC6H5-nFn (n = 2–5) and TiCl4 in petroleum ether (40–60°C) at 0°–10°C. These complexes are characterized by elemental analyses and IR, 1H, and 19F NMR spectroscopy. Unlike the reported5 complex Si(NHC6H4F-o)4.3TiCl4, these are non-ionic in nature. All complexes give double adducts with CH3NO2 and CH3CN within 24 h.

Rapid quantitation of cyclophosphamide metabolites in plasma by liquid chromatography–mass spectrometry

A method is described for the quantification of two metabolites of cyclophosphamide, specifically 4-hydroxycyclophosphamide (HCy), and carboxyethylphosphoramide mustard (CEPM). Plasma HCy is derivatized to the phenylhydrazone which is quantitated by LC-MS monitoring the chloride adduct of the derivative. The LLOQ based on material applied to the system is approximately 20 fmol. Plasma CEPM concentration is determined using LC-MS with a deuterated internal standard. Both assays have 50-fold dynamic range and require less than 4h to complete. The development of this rapid analytical method makes it feasible to adjust the dose of cyclophosphamide based on the pharmacokinetic disposition of HCy and CEPM in hopes of decreasing nonrelapse mortality in cancer patients.

A Novel Chiral Ferrocene-Based Amidine/Amidinato Ligand and Its Rhodium Complexes

The N,N‘-bisferrocenyl-substituted chiral formamidine 1 (N,N‘-bis[(S)-2-{(1R)-1-(diphenylphosphino)ethyl}ferrocen-1-yl]formamidine) was prepared from commercially available {(1R)-1-(dimethylamino)ethyl}ferrocene by a multistep procedure in an overall yield of 29%. Deprotonation of 1 followed by addition of [Rh2Cl2(COD)2] yielded the (formamidinato)rhodium(I) complex 2 [(N,N‘-bis[(S)-2-{(1R)-1-(diphenylphosphino)ethyl}ferrocen-1-yl]formamidinato)rhodium(I)]. Direct reaction of formamidine 1 with [Rh2Cl2(COD)2] led to complex 10 [(κ-N,P-bis[(S)-2-{(1R)-1-(diphenylphosphino)ethyl}ferrocen-1-yl]formamidine)(chloro)(η4-1,5-cyclooctadiene)rhodium(I)], which was converted to 2 upon addition of base. Oxidative addition of methyl chloride or methyl iodide to 2 yielded the trans adducts 11 [(N,N‘-bis[(S)-2-{(1R)-1-(diphenylphosphino)ethyl}ferrocen-1-yl]formamidinato)(chloro)(methyl)rhodium(III)] and 12 [(N,N‘-bis[(S)-2-{(1R)-1-(diphenylphosphino)ethyl}ferrocen-1-yl]formamidinato)(iodo)(methyl)rhodium(III)], the configurations of which were determined by means of NMR and, in the case of the Rh(III) methyl chloride adduct 11, by X-ray analysis.

Synthesis and crystal structure of mercury(II) chloride–ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid) adduct

A mercury(II) chloride adduct of ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid), [HgCl2 (C9H6INO4)·H2O] has been synthesized and characterized by X-ray diffraction analysis and spectroscopic studies. The compound crystallizes in P21/c space group, a = 8.919(3), b = 23.216(3), c = 7.714(3) Å, β = 95.79(3)°. The coordination geometry around mercury is distorted square planar [(2+2) coordination] with two short Hg–Cl bonds [2.308(2) and 2.309(18) Å] and two long Hg–O(sulfonate) [2.738(4) Å] and Hg–O(water) [2.889(4) Å] bonds. The sulfonic group is deprotonated, the proton having migrated to the quinoline N atom that forms intermolecular hydrogen bonds. The inversion related organic ligands are stacked over one another. The crystal structure is further stabilized by a C–H···O, O–H···O and N–H···O hydrogen bonds.