Methylation <i>in vitro</i> using commercially available COMT presented by the spectra of organic phases.

<p>(A) OLDA with COMT (continuous line); OLDA without COMT (dashed line); and <i>O</i>-Me-OLDA alone, a presumed reaction product, (dotted line). (B) OLDA with COMT (continuous line) and 1∶1 artificial mixture of OLDA and <i>O</i>-Me-OLDA (dotted line). The identity of the two spectra in Panel B points to the presence of OLDA and <i>O</i>-Me-OLDA in the reaction mixture. (C) Spectrum of the organic phase of the control mixture with no COMT added, incubated for the same length of time as was the full reaction with COMT.</p

Structural Elucidation of Specific Noncovalent Association of Folic Acid with Native Cyclodextrins Using an Ion Mobility Mass Spectrometry and Theoretical Approach

The combination of ion mobility mass spectrometry studies and theoretical calculations including docking studies permitted a detailed structural description of noncovalent complexes of folic acid (FA) and native cyclodextrins (α-CD, β-CD, and γ-CD). The mode of noncovalent association depended on the cavity size of the cyclodextrin. The structure of FA/α-CD represented the exclusion complex in which the aminobenzoic moiety and the aromatic pteridine ring of folic acid remain outside the cyclodextrin cavity, while the glutamate residue is anchored in the interior of the α-cyclodextrin. A rotaxane-type structure was proposed for the FA/β-CD complex with the aminobenzoic part of FA being trapped in the central cavity of β-CD. The glutamate residue and the aromatic pteridine ring interact with the primary and secondary rim hydroxyl residues, respectively, enhancing complex stability. Two possible structures of FA/γ-CD were suggested, the first one being analogous to the FA/β-CD complex and the second one being more stablein which the aromatic pteridine ring penetrates into the CD cavity while the glutamate residue with the aminobenzoic part of FA is exposed to the cone exterior of CD at its wider edge. Further insight into the association behavior of the folic acid toward cyclodextrins evaluated by thermodynamic calculations indicates that the process is highly exothermic. The complex stability increased in the order FA/α-CD < FA/β-CD < FA/γ-CD. This order is consistent with the previously determined relative gas-phase stability established based on the dissociation efficiency curves of the FA/CD complexes

Improved UHPLC-MS/MS Methods for Analysis of Isoprene-Derived Organosulfates

Secondary organic aerosol (SOA) is an important yet not fully characterized constituent of atmospheric particulate matter. A number of different techniques and chromatographic methods are currently used for the analysis of SOA, so the comparison of results from different laboratories poses a challenge. So far, tentative structures have been suggested for many organosulfur compounds that have been identified as markers for the formation of SOA, including isoprene-derived organosulfates. Despite the effectiveness and robustness of LC-MS/MS analyses, the structural profiling of positional isomers of recently discovered organosulfates with molecular weights (MWs) of 214 and 212 from isoprene was entirely unsuccessful. Here, we developed a UHPLC combined with high-resolution tandem mass spectrometric method that significantly improves the separation efficiency and detection sensitivity of these compounds in aerosol matrices. We discovered that selection of the proper solvent for SOA extracts was a key factor in improving the separation parameters. Later, we took advantage of the enhanced sensitivity, combined with a short scan time window, to perform detailed structural mass-spectrometric studies. For the first time, we elucidate a number of isomers of the MW 214 and the MW 212 organosulfates and provide strong evidence for their molecular structures. The structure of trihydroxyketone sulfate MW 214 that we propose has not been previously reported. The methods we designed can be easily applied in other laboratories to foster an easy comparison of related qualitative and quantitative data obtained throughout the world

CID spectrum (recorded in the negative ion mode) of (A) a dedicated PS containing 30∶2 (<i>sn</i>-1) and 20∶2 (<i>sn</i>-2) fatty acyl residues.

<p>Δ 20∶2 elimination of eicosadienoic acid, Δ 20∶2-H₂O–elimination of eicosadienoic ketene and (B) a given PE species with the following fatty acyl combinations: 28∶1/20∶2; 30∶2/18∶1.</p

31P NMR spectrum and one-dimensional TLC profile of <i>A. castellanii</i> phospholipids.

<p>Left: 242.88 MHz ³¹P NMR spectrum of the organic extract of <i>A. castellanii</i>. Assignments and chemical shifts are indicated in the spectrum. The chemical structures of a phospholipid and a lysophospholipid is shown. R stands for the different head groups, while R₁ and R₂ denote the different carbon chains in the <i>sn</i>-1 and <i>sn</i>-2 position of the glycerol back bone. Chemical structures of the head groups are shown on top of the corresponding peak. Right: One-dimensional TLC profile of <i>A. castellanii</i> phospholipids in comparison with a standard PL mixture that contains the same amounts of all indicated PL. TLC plates were developed in a solvent mixture consisting of chloroform∶methanol∶acetic acid∶acetone∶water (35∶25∶4∶14∶2, v/v/v/v/v). Abbreviations used in peak/spot assignments: CL, cardiolipin; LPC, lyso-phosphatidylcholine; LPE, lyso-phosphatidylethanolamine; PA, phosphatidic acid; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; PI, phosphatidylinositol; PS, phosphatidylserine; SM, sphingomyelin. For details see text.</p

Content (given in mol %) of the fatty acyl residues of each phospholipid class of <i>A. castellanii</i>.

<p>Data were determined by GC/MS analysis of the FAs methyl esters subsequent to alkaline hydrolysis of the corresponding lipid class. Standard deviations of all measurements are estimated to be of the order of ±5%.</p><p>*The position of double bonds was already determined in a previous paper <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101243#pone.0101243-PalusinskaSzysz1" target="_blank">[11]</a>, tr – trace (<0.5%).</p

Highly Phosphorescent Cyclometalated Iridium(III) Complexes for Optoelectronic Applications: Fine Tuning of the Emission Wavelength through Ancillary Ligands

A series of novel, highly phosphorescent cyclometalated iridium­(III) complexes of type [(X₂C^N)₂Ir­(Q₂bpy)]⁺PF₆^– (where X₂C^N is 2-phenylpyridine or 2-(2,4-difluorophenyl)­pyridine anion and Q₂bpy are 4,4′-bifunctionalized 2,2′-bipyridines) is presented. The complexes were fully characterized by means of NMR spectroscopy, high-resolution mass spectrometry (HRMS), cyclic voltammetry, and UV–vis. For several compounds also the crystallographic structures were obtained. The cyclometalates exhibited efficient photoluminescence at 298 K both in solution and in the solid state with good intensity and color purity. The emission wavelength range covered almost the whole visible spectrum and was strongly correlated with the EWG/ERG character of the Q substituent in the ancillary ligand. For further insight into the electronic structure of the complexes, a comprehensive electrochemical support (CV) was introduced, and finally, it was confronted with theoretical background using a density functional theory approach together with time-dependent calculations of the excited states

Nile Red staining of yeast lipid particles.

<p>Visualization of membranes composed of glycerophospholipids (red emission) and neutral lipids, triacyglycerols and steryl esters, in lipid particles (green emission). Cells were cultured overnight. The media were then supplemented with either 100 µM simvastatin or buffer and the cells were further grown with shaking for two hours at 30°C. To localize neutral lipids and glycerophospholipids in yeast cells, Nile Red staining was performed. Horizontal panels: upper glycrophospholipids at 543 nm excitation and 610 nm emission, middle neutral lipids at 488 nm excitation and 515/530 nm emission, lower merge of above panels. Vertical panels: B cells cultivated in buffer, S cells incubated for 2 h in buffer with simvastatin.</p

Two dimensional chromatography of glycerophospholipids.

<p>The levels of all major glycerophospholipids were diminished by treatment with simvastatin. Panels: 1, 3, 5 glycerophospholipids from cells harbouring the wild-type yeast, or the wild-type or mutated <i>hHMGR</i> gene, respectively. Panels 2, 4, 6 glycerophospholipids from simvastatin treated cells harbouring the wild-type yeast, or the wild-type or mutated <i>hHMGR</i> gene, respectively. Abbreviations: PC phosphtidylcholine, PE phosphtidylethanolamine, PS phosphatidylserine, PI phosphtidylinositol, PA phosphtidic acid, LP lysoglycerophospholipid, FA fatty acid, NL neutral lipids.</p

Decrease in sterols and squalene after simvastatin treatment.

<p>Lipids extracted from yeast cells were subjected to alkaline hydrolysis, purified and analysed by GC/MS.</p><p>Wt, wild-type yeast; H, yeast harbouring wild-type <i>hHMGR</i> gene; h, yeast harbouring the mutated <i>hHMGR</i> gene.</p