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  • Chemistry  (9)
  • field desorption.  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    Mass spectrometric studies of underivatized polyphenolic glycosides
    Amsterdam : Elsevier
    Phytochemistry 24 (1985), S. 575-580 
    Details
    ISSN: 0031-9422
    Schlagwort(e): Flavonoids ; desorption chemical ionization ; fast atom bombardment ; field desorption. ; mass spectrometry ; xanthone glycosides
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0031-9422(00)80769-4
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  • 2
    Digitale Medien
    Digitale Medien
    Direct stereochemical assignment of sugar subunits in naturally occurring glycosides by low energy collision induced dissociation. Application to papulacandin antibiotics (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 441-446 
    Details
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A tandem mass spectrometric method is described which allows the assignment of stereochemistry to fragment ions comprising intact sugar subunits of larger glycosides without chemical degradation and product isolation by chromatography. The approach relies on the mass selection of the ‘sugar ion’ of interest followed by analysis of stereoselective fragmentation induced by low-energy collisional activation. The daughter ion spectra provide configurational fingerprints of the selected sugar ions which can be matched for identity with reference spectra obtained from suitable precursors of known stereochemistry. Glucose, mannose and galactose furnished the required set of the most important reference ions. By using peracetyl (and perdeuterioacetyl) derivatives, galactose was readily identified as the glycosidic sugar constituent of the (known) antibiotic papulacandin B and a further (unknown) congener.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200150805
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  • 3
    Digitale Medien
    Digitale Medien
    Tandem mass spectrometric analysis of fixed-charge derivatized oligosaccharidesPresented at the 12th IMSC, Amsterdam, August 1991. (1994)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 29 (1994), S. 713-719 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Various derivatives of a set of three isomeric (linear and branched) pentasaccharides (LNF-1, LNF-2 and LNF-3) were prepared and investigated by high-performance tandem mass spectrometry in order to compare their collision-induced dissociation (CID) behaviour. The fast atom bombardment tandem mass spectra of [M + H]+ ions of peracetylated derivatives mainly display fragments containing the non-reducing terminus (B-type ions) and allow a straightforward assignment of sugar sequence and branching together with the identification of some interglycosidic linkages. Permethylated derivatives, which better accommodate the mass range of tandem mass spectrometers in the case of larger oligosaccharides, yield similar results, i.e. predominance of B ions, but the necessary information has to be retrieved from incomplete Bi and Yi ion series. By contrast, CID of permethyl or peracetyl derivatives carrying a preformed charge due to prior reductive amination of the oligosaccharides with trimethyl(p-aminophenyl)ammonium chloride yields exclusively fragment ions comprising the reducing end. In this case, the four distinct series of fragments observed involve charge-remote fragmentation processes. As a consequence, the spectral patterns are not significantly affected by the nature of the sugar O-substituents additionally introduced (i.e. methyl or acetyl).
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210291204
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  • 4
    Digitale Medien
    Digitale Medien
    High performance tandem mass spectrometry for sequence, branching and interglycosidic linkage analysis of peracetylated oligosaccharides (1990)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1990), S. 390-392 
    Details
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200190611
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  • 5
    Digitale Medien
    Digitale Medien
    Characterization and direct glycoform profiling of a hybrid plasminogen activator by matrix-assisted laser desorption and electrospray mass spectrometry: Correlation with high-performance liquid chromatographic and nuclear magnetic resonance analyses of the released glycansPresented in part at the Kyoto '92 International Conference on Biological Mass Spectrometry, September 20-24, 1992 (see ref. 2). (1994)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1994), S. 330-338 
    Details
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Mass spectrometric analysis of the recombinant hybrid plasminogen activator K2tu-PA at the native glycoprotein and corresponding protein level (high mass) is described. For gross structural characterization of the major glycotypes present, a combination of enzymatic degradation and matrix-assisted laser desorption mass spectrometric analysis of the products proved convenient. In this way, mono- and di-N-glycosylated one- and two-chain molecules, unresolved in the spectra of native material, were identified, with the one-chain type monoglycosylated at Asn247 representing the major component. Actual detection of resolved original glycoforms, or unresolved groups thereof when composed of isobaric species, and their assignments regarding antennicity and degree of sialylation were possible by electrospray mass spectrometry for the major monoglycosylated one-chain species. Desialation also allowed detection of the diglycosylated one-chain species as a minor constituent. The electrospray mass spectrometric results were correlated with structural and quantitative data available from a parallel high-performance liquid chromatographic and 1H nuclear magnetic resonance study performed at the glycan (low mass) level on liberated individual carbohydrate components. The results of the two studies showed full consistency in all respects amenable to evaluation, i.e. excellent agreement for the assignments of antennicity and degree of sialylation of the major glycan components, and good agreement for the determination of proportions in which these were present in the major monoglycosylated glycoprotein. This provided a sound basis for direct glycoform profiling by electrospray mass spectrometry. Typical applications to batch quality control and to structural characterization of nonstandard material are shown.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200230606
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  • 6
    Digitale Medien
    Digitale Medien
    Behaviour of isomeric methyl ethyl and ethyl methyl halosuccinates under electron impact. Elimination of a halogen atom by a multi-step mechanism (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 26 (1991), S. 793-798 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electron impact mass spectra of isomeric methyl ethyl and ethyl methyl halosuccinates (X = Cl and Br) are surprisingly different. Only the isomers with the ethyl group remote from the halogen give rise to [M - X]+ ions. A low-energy collision-induced dissociation study of deuterium-labelled analogues of the former isomers indicates that the [M - X]+ ions are mixtures of protonated methyl ethyl maleate (major component, 〉 85%) and fumarate, and the loss of the halogen atom is a multi-step process including at least two specific hydrogen transfers. Migration of a β-hydrogen atom to the carbonyl oxygen within the ethoxycarbouyl group produces a primary radical site in a distonic intermediate which, by subsequent abstraction of a hydrogen atom from C(3), triggers the ejection of X from C(2) with concomitant double bond formation. Whereas in the other isomer an [M - X]+ ion is absent or negligible, a characteristic double loss of C2H4 and CO2 is observed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210260917
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  • 7
    Digitale Medien
    Digitale Medien
    Identification of interglycosidic linkages and sugar constituents in disaccharide subunits of larger glycosides by tandem mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 24 (1989), S. 357-359 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210240515
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  • 8
    Digitale Medien
    Digitale Medien
    Application of low energy CID in the determination of structures of [M - halogen]+ ions obtained from diethyl halosuccinates under electron impact (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1987), S. 61-63 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Low energy collision induced dissociation (CID) spectra indicate that m/z 173 ions formed by the loss of a halogen atom from diethyl chloro- and bromo-succinate under electron impact are mixtures of O-protonated diethyl maleate (〉90%) and fumarate (〈10 %). Hydrogen migration precedes the C-halogen bond cleavage in these cases. The low energy CID spectrum of the m/z 173 [M—I]+ ion obtained from diethyl iodosuccinate shows that only a small fraction of the [M—I]+ ions are the O-protonated species formed by hydrogen migration. The results of this study demonstrate the potential of low energy CID in the determination of structure (including configuration) of gas phase ions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210220202
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  • 9
    Digitale Medien
    Digitale Medien
    Tandem mass spectrometry in the structural analysis of an oviposition-deterring pheromonePresented at the 10th Informal Meeting on Mass Spectrometry, Padova, 6-8 April 1992. (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 1276-1283 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The potential of tandem mass Spectrometry (MS/MS) as a stand-alone technique in the structural analyses of an oviposition-deterring pheromone (ODP, 1) is reviewed. Two facets of the salt-like glycolipid structure of 1 were of major interest in this context: the substitution pattern of the lipid backbone (15-glucosyioxy-8-hydroxypalmitate) and, more specifically, the configurational identity of the sugar portion (glucopyra nose). Throughout this study, trideuterioacetyl derivatives of ODP (1 → pentakis(trideuterioacetyl)-ODP la) and the reference substrates were used. Probing of the sugar moiety by fast atom bombardment (FAB) and both low- and high-energy collision-induced dissociation (CID) of B2-type sugar ions surprisingly failed as a single exception within a larger number of glycosidic substrates subjected to this approach. However, electrospray ionization (ESI) of la with the formation of the sugar ions in the gas phase by ‘first-stage’ CID before mass selection circumvented this difficulty and provided an unambiguous and sensitive probe for sugar stereochemistry. When studying the ODP molecule as a whole, FAB-generated M-like ions such as [M - H]-, [M + Na]+ and [M - H + 2Na]+ were subjected to high-energy CID using a four-sector tandem mass spectrometer. Analyses of simple model substrates such as the 12-trideuterioacetoxystearate anion facilitated the interpretation of the distinct charge-remote fragmentation (CRF) behaviour of la. Whereas all M-like species provided complete records of the lipid portion of la and its oxygenation pattern, only the sodiated cations allowed reliable location of the individual substituents. In these latter species complementary series of ‘sequence ions’ were observed that incorporated either the taurine or the sugar terminus and thus reflected CRF for both alternatives of terminal charge fixation.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210271121
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  • 10
    Digitale Medien
    Digitale Medien
    Mechanism of electron impact ionization-induced halogen elimination from 2-methyl-2-bromosuccinatesDedicated to Professor H. Budzikieiwcz on the occasion of his 60th birthday. (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 230-234 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electron impact-induced halogen elimination from 2-methyl-2-bromosuccinates occurs only in the one of the two isomeric methyl ethyl esters in which the ethoxycarbonyl group is remote from the halogen, in analogy with the corresponding previously reported halosuccinates. However, the occurrence of debromination in dimethyl 2-methyl-2-bromosuccinate contrasts with the behaviour of dimethyl bromosuccinate, indicating different mechanisms for this process in the two systems. Collision-induced dissociation (CID) and deuterium labelling studies led to the conclusion that a hydrogen transfer from the 2-methyl group to a carbonyl precedes the elimination of Br· from dimethyl 2-methyl-2-bromosuccinate, resulting in a protonated dimethyl itaconate structure for the [M - Br]+ ion. An analogous process is the major route leading to [M - Br]+ ion from 1-methyl-4-ethyl 2-methyl-2-bromosuccinate. In this case deuterium labelling and CID measurements indicated a significant contribution of methyl ethyl citraconate and possibly mesaconate owing to partial operation of a mechanism similar to that reported for 1-methyl-4-ethyl 2-bromosuccinate.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210280315
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