MALDI-TOF MS Measurements Research Articles

Electrochemical Dissolution and Redeposition of Electropolymerized Polyindole Film

Abstract An electropolymerized polyindole film was solubilized into a dichloromethane solution by its electrochemical reduction, and the electrochemical reoxidation of the soluble species produced the film again on the electrode surface. These dissolution and redeposition behavior were investigated by using cyclic voltammetry, UV–vis, NMR, FT-IR, and MALDI-TOFMS measurements.

Self-assembled cyclic boron-dipyrrin oligomers

Self-assembled cyclic boron-dipyrrin oligomers 3-5 obtained by the reaction of catecholyldipyrrin with boron trichloride were characterized by 1H NMR, MALDI-TOF MS, and X-ray measurements and the interaction between 3 and alkali metal ions was examined.

Two novel oligosaccharides isolated from a beverage produced by fermentation of a plant extract

An extract from 50 kinds of fruits and vegetables was fermented to produce a new beverage. Natural fermentation of the extract was carried out mainly by lactic acid bacteria ( Leuconostoc spp.) and yeast ( Zygosaccharomyces spp. and Pichia spp.). Two new saccharides were found in this fermented beverage. The saccharides were isolated using carbon–Celite column chromatography and preparative high performance liquid chromatography. Gas liquid chromatography analysis of methylated derivatives as well as MALDI-TOF MS and NMR measurements were used for structural confirmation. The 1H and 13C NMR signals of each saccharide were assigned using 2D-NMR including COSY, HSQC, HSQC-TOCSY, CH 2-HSQC-TOCSY, and CT-HMBC experiments. The saccharides were identified as β- d-fructopyranosyl-(2→6)-β- d-glucopyranosyl-(1→3)- d-glucopyranose and β- d-fructopyranosyl-(2→6)-[β- d-glucopyranosyl-(1→3)]- d-glucopyranose.

Three novel oligosaccharides synthesized using Thermoanaerobacter brockii kojibiose phosphorylase

BackgroundRecently synthesized novel oligosaccharides have been produced primarily by hydrolases and glycosyltransferases, while phosphorylases have also been subject of few studies. Indeed, phosphorylases are expected to give good results via their reversible reaction. The purpose of this study was to synthesis other novel oligosaccharides using kojibiose phosphorylase.ResultsThree novel oligosaccharides were synthesized by glucosyltransfer from β-D-glucose 1-phosphate (β-D-G1P) to xylosylfructoside [O-α-D-xylopyranosyl-(1→2)-β-D-fructofuranoside] using Thermoanaerobacter brockii kojibiose phosphorylase. These oligosaccharides were isolated using carbon-Celite column chromatography and preparative high performance liquid chromatography. Gas liquid chromatography analysis of methyl derivatives, MALDI-TOF MS and NMR measurements were used for structural characterisation. The 1H and 13C NMR signals of each saccharide were assigned using 2D-NMR including COSY (correlated spectroscopy), HSQC (herteronuclear single quantum coherence), CH2-selected E-HSQC (CH2-selected Editing-HSQC), HSQC-TOCSY (HSQC-total correlation spectroscopy) and HMBC (heteronuclear multiple bond correlation).ConclusionThe structure of three synthesized saccharides were determined, and these oligosaccharides have been identified as O-α-D-glucopyranosyl-(1→2)-O-α-D-xylopyranosyl-(1→2)-β-D-fructofuranoside (saccharide 1), O-α-D-glucopyranosyl-(1→2)-O-α-D-glucopyranosyl-(1→2)-O-α-D-xylopyranosyl-(1→2)-β-D-fructofuranoside (saccharide 2) and O-α-D-glucopyranosyl-(1→[2-O-α-D-glucopyranosyl-1]2→2)-O-α-D-xylopyranosyl-(1→2)-β-D-fructofuranoside (saccharide 3).

Isolation and Identification of Novel Tri- and Tetra-saccharides Synthesized by Thermoanaerobacter brockii Kojibiose Phosphorylase

Novel tri- and tetra-saccharides were synthesized by glucosyltransfer from β-D-glucose 1-phosphate (β-D-G1P) to palatinose using Thermoanaerobacter brockii kojibiose phosphorylase. There saccharides were isolated using carbon-Celite column chromatography and preparative high performance liquid chromatography. Gas liquid chromatography analysis of methyl derivatives, MALDI-TOF MS and NMR measurements were used for structural confirmation of the saccharides. The 1H and 13C NMR signals of the saccharides were assigned using 2D-NMR including COSY, HSQC, HSQC-TOCSY and HMBC. These oligosaccharides were identified as 2G-α-D-glucopyranosyl-palatinose; O-α-D-glucopyranosyl-(1→2)-O-α-D-glucopyranosyl-(1→6)-D-fructofuranose and 2G(2-α-D-glucopyranosyl)2-palatinose; O-α-D-glucopyranosyl-(1→2)-O-α-D-glucopyranosyl-(1→2)-O-α-D-glucopyranosyl-(1→6)-D-fructofuranose.

Sol–gel films for DNA microarray applications

Sol–gel derived (3-aminopropyl)trimethoxysilane–tetramethoxysilane ((CH3O)3SiCH2CH2CH2NH2–Si(OCH3)4) hybrid films are shown to have properties that make the films suitable for DNA microarray applications. The essential characteristics of the films are discussed on the basis of binding of aminated 25-mer oligonucleotide DNA to the films via 1,4-phenylenediisothiocyanate linkering. The binding of DNA onto the films is shown to depend on films' composition having an optimum where the binding is substantially superior compared to commercial analogues. The relevant properties of the films are characterized by AFM, FTIR and MALDI-TOF MS measurements.

Protein Complexes in the Archaeon Methanothermobacter thermautotrophicus Analyzed by Blue Native/SDS-PAGE and Mass Spectrometry

Methanothermobacter thermautotrophicus is a thermophilic archaeon that produces methane as the end product of its primary metabolism. The biochemistry of methane formation has been extensively studied and is catalyzed by individual enzymes and proteins that are organized in protein complexes. Although much is known of the protein complexes involved in methanogenesis, only limited information is available on the associations of proteins involved in other cell processes of M. thermautotrophicus. To visualize and identify interacting and individual proteins of M. thermautotrophicus on a proteome-wide scale, protein preparations were separated using blue native electrophoresis followed by SDS-PAGE. A total of 361 proteins, corresponding to almost 20% of the predicted proteome, was identified using peptide mass fingerprinting after MALDI-TOF MS. All previously characterized complexes involved in energy generation could be visualized. Furthermore the expression and association of the heterodisulfide reductase and methylviologen-reducing hydrogenase complexes depended on culture conditions. Also homomeric supercomplexes of the ATP synthase stalk subcomplex and the N5-methyl-5,6,7,8-tetrahydromethanopterin:coenzyme M methyltransferase complex were separated. Chemical cross-linking experiments confirmed that the multimerization of both complexes was not experimentally induced. A considerable number of previously uncharacterized protein complexes were reproducibly visualized. These included an exosome-like complex consisting of four exosome core subunits, which associated with a tRNA-intron endonuclease, thereby expanding the constituency of archaeal exosomes. The results presented show the presence of novel complexes and demonstrate the added value of including blue native gel electrophoresis followed by SDS-PAGE in discovering protein complexes that are involved in catabolic, anabolic, and general cell processes.

Electrochemical and chemical synthesis and characterization of sulfonated poly(3,4-ethylenedioxythiophene): A novel water-soluble and highly conductive conjugated oligomer

Electrochemical and chemical polymerization of a 3,4-ethylenedioxythiophene derivative bearing a sulfonate group (EDTS) is reported. The electrochemical polymer, poly(EDTS), which is very soluble in water, has been produced both from acidic water, resulting in the solution form, and from acetonitrile using additional perchloric acid in 1:1 ratio to the monomer, resulting in the production of polymer films. Both forms were characterized by cyclic voltammetry, UV-Vis spectroscopy, EQCM analysis, MALDI-TOF MS and conductivity measurements, and show high conductivity (0.5–10 S · cm−1) and high solubility in water (> 10%). Poly(EDTS) was also prepared by chemical polymerization with Fe(OTs)3 in water to yield once more a water-soluble and conductive (1–5 S · cm−1) polymer.

Sample deposition device for off-line combination of supercritical fluid chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A new sample deposition device for off-line SFC-MALDI combination of supercritical fluid chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was assembled. This device was successfully applied to the detailed characterization of synthetic silicone oils. SFC was used to separate samples of silicone oils on micropacked capillary columns and to determine their molecular mass distribution. The separated fractions for the identification studies were obtained from SFC runs at defined time intervals. Using the constructed deposition device, these fractions were sprayed directly from the restrictor on the target probe covered with a proper matrix. MALDI-TOF MS was used for the identification of individual oligomers in the separated fractions and also in the unfractionated sample. The determined molecular mass distributions based on supercritical fluid chromatography with flame ionization detector, MALDI-TOF MS, and combined SFC-MALDI measurements were compared and the results were in a good agreement. The sample deposition device is based on a common plotter unit, complemented by a microcontroller PIC16C84. The unit is connected by an RS-232 interface to a PC with the main control software running under MS Windows. The new sample deposition device made the off-line combination SFC-MALDI simpler, faster, and more sensitive.