A one‐step matrix application method for MALDI mass spectrometry imaging of bacterial colony biofilms

Matrix‐assisted laser desorption/ionization imaging of biofilms cultured on agar plates is challenging because of problems related to matrix deposition onto agar. We describe a one‐step, spray‐based application of a 2,5‐dihydroxybenzoic acid solution for direct matrix‐assisted laser desorption/ionization imaging of hydrated Bacillus subtilis biofilms on agar. Using both an optimized airbrush and a home‐built automatic sprayer, region‐specific distributions of signaling metabolites and cannibalistic factors were visualized from B. subtilis cells cultivated on biofilm‐promoting medium. The approach provides a homogeneous, relatively dry coating on hydrated samples, improving spot to spot signal repeatability compared with sieved matrix application, and is easily adapted for imaging a range of agar‐based biofilms. Copyright © 2016 John Wiley & Sons, Ltd.     

Silanization of inner surfaces of nanoelectrospray ionization emitters for reduced analyte adsorption

During the course of nanoelectrospray ionization (nanoESI) of substance P, an unusual type of signal reduction was observed with flow rates <10 nL/min. This reduction in signal appears to be induced by the adsorption of positively charged analytes onto negatively charged free silanol groups on the inner surface of emitters; analytes with higher pI values (such as substance P) exhibit greater tendency for adsorption. Support for this hypothesis is demonstrated by the decrease in signal reduction in the presence of concentrated salts or for emitters whose internal silanols have been covalently silanized. Emitters treated with hexamethyldisilazane or 3-aminopropyltriethoxysilane showed higher analyte signals for substance P than untreated emitters, suggesting a reduction of analyte adsorption onto the inner walls of silanized emitters. The efficacy of reduced peptide adsorption was demonstrated for emitters silanized with 3-aminopropyltriethoxysilane using a simple peptide mixture as well as a more complex peptide mixture (a tryptic digest of horse hemoglobin).     

Synthesis of farnesol isomers via a modified Wittig procedure

[structure: see text] The four olefin stereoisomers of farnesol have been synthesized from readily available nerylacetone or commercial geranylacetone. A new variation on the use of beta-oxido ylides favored the (2Z)-stereoisomers, whereas the (2E)-isomers were obtained through a classical Horner-Wadsworth-Emmons condensation with triethyl phosphonoacetate and reduction of the resulting ester.     

Coherence length of an elongated condensate

We measure the spatial correlation function of Bose-Einstein condensates in the cross-over region between phase-coherent and strongly phase-fluctuating condensates. We observe the continuous path from a Gaussian-like shape to an exponential-like shape characteristic of one-dimensional phase-fluctuations. The width of the spatial correlation function as a function of the temperature shows that the condensate coherence length undergoes no sharp transition between these two regimes.     

Synthesis and Biological Evaluation of the Antimicrobial Natural Product Lipoxazolidinone A

Natural products have historically been a major source of antibiotics and therefore novel scaffolds are constantly of interest. The lipoxazolidinone family of marine natural products, with an unusual 4‐oxazolidinone heterocycle at their core, represents a new scaffold for antimicrobial discovery; however, questions regarding their mechanism of action and high lipophilicity have likely slowed follow‐up studies. Herein, we report the first synthesis of lipoxazolidinone A, 15 structural analogues to explore its active pharmacophore, and initial resistance and mechanism of action studies. These results suggest that 4‐oxazolidinones are valuable scaffolds for antimicrobial development and reveal simplified lead compounds for further optimization.     

Synthesis and activity of fluorescent isoprenoid pyrophosphate analogues

New fluorescent analogues of farnesol and geranylgeraniol have been prepared and then converted to the corresponding pyrophosphates. These analogues incorporate anthranylate or dansyl-like groups anchored to the terpenoid skeleton through amine bonds that would be expected to be relatively stable to metabolism. After addition of the alcohols or the pyrophosphates to the culture medium, their fluorescence is readily observed inside a human-derived leukemia cell line. Enzyme assays have revealed that the farnesyl pyrophosphate analogue is an inhibitor of FTase, while the corresponding alcohol is not. These results, together with Western blot analyses of cell lysates, indicate that the farnesyl pyrophosphate analogue penetrates the cells as an intact pyrophosphate and that it does so at a biologically relevant concentration.     

GTKDynamo: A PyMOL plug‐in for QC/MM hybrid potential simulations

Hybrid quantum chemical/molecular mechanical (QCMM) potentials are very powerful tools for molecular simulation. They are especially useful for studying processes in condensed phase systems, such as chemical reactions that involve a relatively localized change in electronic structure and where the surrounding environment contributes to these changes but can be represented with more computationally efficient functional forms. Despite their utility, however, these potentials are not always straightforward to apply since the extent of significant electronic structure changes occurring in the condensed phase process may not be intuitively obvious. To facilitate their use, we have developed an open‐source graphical plug‐in, GTKDynamo that links the PyMOL visualization program and the pDynamo QC/MM simulation library. This article describes the implementation of GTKDynamo and its capabilities and illustrates its application to QC/MM simulations. © 2013 Wiley Periodicals, Inc.     

Densitometric—HPTLC Method Development and Analysis of Anthocyanins from Acai (Euterpe oleracea Mart.) Berries and Commercial Products

JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatographic (HPTLC) method was developed for the quantification of two anthocyanins, viz.,...