Fast Atom Bombardment Mass Research Articles

Soft ionization techniques in mass spectrometry of distamycin and some analogues.

The results obtained using three different soft ionization techniques (field desorption (FD), fast atom bombardment (FAB) and desorption chemical ionization (DCI] on the antiviral antibiotic distamycin and on some analogues are reported. FAB mass spectra show more intense molecular ion and more regular fragmentation while FD and DCI mass spectra are dominated by thermally originated fragments. Information furnished by the three systems are different and complementary.

Further novel amido sugars within the glycopeptidolipid antigens of Mycobacterium avium.

The individual serovars of the Mycobacterium avium complex, a source of serious and persistent infections in individuals with underlying immune deficiencies, also present an extraordinary set of novel sugar epitopes as part of their type-specific glycopeptidolipid surface antigens. Californium desorption-mass spectrometry has been successfully applied to the holistic glycopeptidolipid antigen of M. avium serovar 12 and its per-O-acetyl derivative, to arrive at the following structure, of molecular mass 1876: (Sequence: see text). The pentasaccharide hapten, released as the tetraglycosyl alditol, was subjected to methylation analysis, absolute configurational analysis, 1H NMR and fast atom bombardment-mass spectrometry to arrive at the structure: 4-(2'-Hydroxy) propionamido-4,6-dideoxy-3-O-Me-Glcp (beta 1----3)-4-O-Me-L-Rhap (alpha 1----3)-L-Rhap (alpha 1----3)-L-Rhap (alpha 1----2)-6-deoxytalitol. Two-dimensional proton correlation spectroscopy was also applied to determine the configuration of the unique distal segment of the oligosaccharide unit. The significance of this structure in the context of the fully elucidated structures of the antigens from 12 of the 31-member M. avium complex is discussed.

Characterization of bis(diphenylphosphino)methane and bis(diphenylphosphinomethyl) phenylphosphine complexes of platinum(II) and palladium(II) by fast-atom-bombardment mass spectrometry

Abstract The positive fast-atom-bombardment (FAB) mass spectra of [M(dppm)X 2 ] dppm = Ph 2 PCH 2 PPh 2 ; M  Pt, X  Cl, Br or I; M  Pd, X  Cl), [M(dpmp)X 2 ] (dpmp = Ph 2 PCH 2 PPhCH 2 PPh 2 ; M  Pt, X  Cl, Br, I or CH 3 ; M  Pd, X  Cl), and Pt(dppm) 2 X 2 (X  Cl, Br, I or PF 6 ) in a 3-nitrobenzyl alcohol matrix, together with electron-impact mass spectra for PPh 3 , dppm and dpmp, are reported. The use of other matrices and different ionization techniques is also discussed. The complexes exhibit fragmentation pathways similar to those of the free ligands, and the wide utility of FAB mass spectrometry for the identification of monomeric platinum and palladium phosphine complexes and salts is clearly demonstrated.

Fast atom bombardment (FAB) and chemical ionization (CI) mass spectrometry of γ-carboxyglutamic acid, 5-substituted-4,4-dicarboxyprolines, and their monodecarboxy derivatives glutamic acid and 5-substituted-4-carboxyprolines

DL-γ-Carboxyglutamic acid (Gla) reacts easily and quantitatively with aldehydes to give the racemic diastereoisomers of 5-substituted-4,4-dicarboxyprolines. After heating at 100 °C for 30 minutes these amino acids lose a carboxyl group from C-γ of Gla and C-4 of the proline ring to give glutamic acid and the racemic diastereoisomers of cyclic analogs of glutamic acid respectively. This paper reports a study of the above-mentioned compounds by using FAB mass spectrometry in comparison with CI analysis. FAB turned out to be an adequate ionization technique for dealing with such nonvolatile and thermolabile amino acids, and may thus allow the development of a rapid and sensitive method for detecting γ-carboxyglutamic acid in urine and in other biological matrices in pathological cases (i.e., renal stones and blood serum).

Synthesis and characterization of carbohydrate-insulin conjugates using desorption ionization mass spectrometry

Blood glycoproteins containing terminal non-reducing D-galactosyl groups have previously been shown to be rapidly cleared from the circulatory system of animals. This occurs by interaction at the asialoglycoprotein receptor of the hepatocytes. We prepared several carbohydrate–insulin conjugates, containing one or more terminal D-galactosyl residues, to study their binding to this receptor. Fast atom bombardment (FAB) and 252Cf plasma desorption (PD) mass spectrometry were used to characterize the conjugates formed when insulin was treated with N-hydroxysuccinimide lactobionate. The synthetic approach, using N-hydroxysuccinimide amino acid esters, is a well-known procedure for peptide synthesis. However, the coupling reaction did not yield the expected lactobionyl insulin products. Instead, each lactobionyl group was accompained by an additional mass increment (115 daltons) in the conjugate structure. PD mass spectrometry verified that the products were intact modified insulins, while FAB mass spectrometry, with computerized peak matching and tandem mass spectrometry, provided the exact mass and structure of the additional mass increment. The two desorption ionization methods provided complementary data enabling the rapid characterization of these unexpected synthetic products.

Characterization of a major neutral glycolipid in PC12 cells as III3Gal alpha-globotriaosylceramide by the method for determining glycosphingolipid saccharide sequence with endoglycoceramidase.

Neutral glycolipids in PC12 cells were examined. A major neutral glycosphingolipid, isolated from a chloroform/methanol extract of the cells, was found to contain only galactose and glucose at a ratio of 3:1 and identified as ceramide tetrahexoside by fast atom bombardment (FAB) mass spectrometry. Its saccharide sequence was determined by a new method developed here using endoglycoceramidase (Ito, M., and Yamagata, T. (1986) J. Biol. Chem. 261, 14278-14282). The glycosphingolipid was digested with endoglycoceramidase to produce oligosaccharide which was subsequently pyridylaminated. The fluorescence-labeled oligosaccharide was digested with a series of specific exoglycosidases and fractionated by high performance liquid chromatography. The 2-aminopyridyl oligosaccharide was hydrolyzed by alpha-galactosidase to give a 2-aminopyridyl oligosaccharide which was identified as 2-aminopyridyl lactose by high performance liquid chromatography, indicating the glycolipid structure to be Gal alpha Gal alpha Gal beta GlcCer. Ceramide trihexoside obtained by limited digestion of the intact glycolipid was clearly identical with ceramide trihexoside obtained from human erythrocytes, according to NMR spectroscopy and methylation analysis. From these and other data on the intact glycolipid, obtained by methylation analysis and NMR spectroscopy, its structure was confirmed as Gal alpha 1-3Gal alpha 1-4Gal beta 1-4Glc beta 1-1Cer, III3-Gal alpha-globotriaosylceramide. This is the first report indicating the presence of this glycosphingolipid in PC12 cells.

Fast atom bombardment mass spectrometry of some anthracycline and bisanthracycline derivatives.

Fast atom bombardment (FAB) mass spectra of daunomycin, four of its derivatives, seven bisanthracyclines and three mixed-functional daunomycin-acridine derivatives are reported. These anthracyclines all exhibited their expected [MH]+ ions and peaks corresponding to the fragmentations which are characteristic of the anthracycline moiety, and in addition the spectra showed enhanced [MH + n]+ (n = 1-4) ions which were attributed to reductive processes occurring in the liquid matrix under FAB conditions. Daunomycin was also observed to form a dimeric cluster ion [M2H]+ together with associated reduced ions under FAB conditions. We have found that FAB mass spectrometry is an ideal method for the qualitative analysis of large, non-volatile derivatives of anthracyclines.

Comparison of electron impact, desorption chemical ionization, field desorption, and fast atom bombardment mass spectra of nine monosubstituted Group VI metal carbonyls

Nine monosubstituted group VI metal pentacarbonyls of the type M(CO)/sub 5/L (where M = Cr, Mo, or W; and L = P(C/sub 6/H/sub 5/)/sub 3/, As(C/sub 6/H/sub 5/)/sub 3/, or Sb(C/sub 6/H/sub 5/)/sub 3/) were synthesized and purified by recrystallization so that they contained no unbound ligands, excess reagents, or other contaminants as measured by high-performance liquid chromatography. Positive ion mass spectra were obtained by electron impact (EI), desorption chemical ionization (DCI), field desorption (FD), and fast atom bombardment (FAB) mass spectrometry. B/E linked scanning was used to confirm the fragmentation pathway in FAB mass spectra. While all four ionization methods formed molecular ions, M/sup +/, the desorption ionization methods tended to produce more abundant molecular ions than EI. FD, for instance, formed molecular ions without any fragmentation. The most abundant fragment ions of the ligand (L) were observed with DCI. FAB spectra contained abundant molecular ions and extensive structural information in ion fragments.

Characterization of glutathione conjugates by fast atom bombardment/tandem mass spectrometry.

The collisionally activated decomposition of [M + H]+ ions, generated by fast atom bombardment (FAB) of glutathione conjugates, has been studied by tandem mass spectrometry (MS/MS) using hybrid sector/quadrupole instruments. Abundant fragments of diagnostic utility were present in the daughter ion spectra. Common fragmentation modes were observed but their relative importance was strongly dependent on the nature of the conjugated species. As an example of a general approach to the characterization of glutathione conjugates in biological samples, the acetaminophen-glutathione conjugate was identified in rat bile, following coadministration of (2H0)- and (2H3)acetaminophen, using the experimental sequence: (i) conventional FAB mass spectrometric analysis, (ii) MS/MS using constant neutral loss (129 u) scanning to identify parent ions corresponding to glutathione conjugates, (iii) MS/MS to yield daughter ion spectra of parents so identified and corresponding to (2H0)- and (2H3)-labeled conjugates.

A determination of the positions of disulphide bonds in Paim I, alpha-amylase inhibitor from Streptomyces corchorushii, using fast atom bombardment mass spectrometry.

Paim I, a protein alpha-amylase inhibitor, is a single-chain polypeptide which consists of 73 amino acids, including 4 half-cystine residues. The positions of disulphide bonds in Paim I have been determined with the combination of enzymatic digestion and fast atom bombardment (FAB) mass spectrometry. Denatured Paim I was digested to peptides with Staphylococcus aureus V8 protease. These peptides were subjected to FAB mass spectrometry, with or without isolation by high-performance liquid chromatography. The positions of disulphide bonds in Paim I were determined from the relative molecular masses of the peptides containing a disulphide bond and by the enzyme specificity of S. aureus V8 protease. It is deduced that Paim I has two disulphide bridges at Cys(8)--Cys(24) and Cys(42)--Cys(70).

Use of fast atom bombardment mass spectrometry for the characterization of nitroaromatic isomers

AbstractPositive and negative ion fast atom bombardment (FAB) mass spectra of some monosubstituted nitroaromatic isomers are reported. Generally ions carresponding to [M + H]+ and M+ are observed in the positive ion FAB spectra; ions such as [M − H] − and M−˙ are observed in the negative ion FAB spectra. The use of FAB mass spectra to distinguish the isomers is discussed. Comparisons of FAB, chemical ionization and electron impact mass spectra of the same isomers (wherever possible) are reported. The structural information obtained in the negative ion FAB spectra complement those obtained in the positive ion FAB spectra.

Composition des lipides complexes de Flavobacterium meningosepticum

The free lipids of Flavobacterium meningosepticum were separated by thin layer chromatography, and the main lipid fractions were analysed by FAB (fast atom bombardment) mass spectrometry. The major products were di-iso-C 15- and iso-C 15-iso-C 17-phosphatidylethanolamine, and two ninhydrine + and phosphorus − fractions. The structures of the latter two fractions were established as ornithine lipids by using MIKE (mass ions kinetic energy) mass spectrometry, GC/MS (gas chromatography coupled with mass spectrometry) and conventional methods. The presence of small amounts of sphingolipids with C 17- and C 16-sphinganines was demonstrated. F. meningosepticum can be distinguished from F. multivorum and F. spiritivorum by easy characterization of the ornithine lipids by thin layer chromatography.

Chetracin A and chaetocins B and C, three new epipolythiodioxopiperazines from Chaetomium spp.

A new dimeric epipolythiodioxopiperazine named chetracin A with two tetrasulfide bridges was isolated from Chaetomium nigricolor and C. retardatum, and the structure (3) proposed chiefly from proton and carbon-13 nuclear magnetic resonance (1H-and 13C-NMR) data was established by X-ray analysis. Two congeners of chaetocin (2) named chaetocins B and C were isolated from C. virescens var. thielabioideum, and were proved tobe homologs with one disulfide and one trisulfide bridge (9) and with two trisulfide bridges (10), respectively, from spectral data, chiefly NMR and fast atom bombardment mass spectrometry/mass spectrometry (FAB MS/MS). The structure-activity relationships observed for the antibacterial activity and cytotoxicity of the related compounds are discussed.

Fast atom bombardment and tandem mass spectrometry of synthetic neuropeptides and their deuterated analogues

Fast atom bombardment and tandem mass spectrometry of synthetic neuropeptides and their deuterated analogues

Fast atom bombardment-mass spectrometry of glycosphingolipids extracted from thin-layer chromatography plates

A method is described for analysis of glycosphingolipids extracted from thin-layer chromatography plates. Mixtures of glycolipids and gangliosides were separated by thin-layer chromatography and the individual bands were eluted, permethylated, and, after purification, analyzed by fast atom bombardment-mass spectrometry. The glycosphingolipids could be characterized from their fast atom bombardment mass spectra in terms of partial monosaccharide sequence, ceramide composition, and molecular weight. The sensitivity of the method allows characterization of 1–5 μg of glycosphingolipid.

Heterogeneity in oligosaccharides from theO-polysaccharide chain of the lipopolysaccharide fromSalmonella typhi 253Ty determined by fast atom bombardment mass spectrometry

Oligosaccharides from theO-polysaccharide chain of theSalmonella typhi 253Ty lipopolysaccharide (LPS) were prepared from delipidated LPS by digestion with bacteriophage P22. The oligosaccharides were separated by gel chromatography into fractions representing monomers to polymers of the basic tetrasaccharide repeating unit. Fractions containing the dimer and the trimer were analysed by fast atom bombardment-mass spectrometry as methylated alditols. The mass spectra clearly showed heterogeneity in terms ofd-glucose substitution of thed-galactose residue in the tetrasaccharide repeating unit: dimers with none, one, or twod-glucosyl branches and trimers with none, one, two, or threed-glucosyl branches were found. This suggests a randomd-glucosylation of theO-polysaccharide chain ofS. typhi 253Ty.

Hue Detector for Column Chromatography

A column chromatograph was made, which has an amorphous integrated diode photo-electric transducer (Sanyo, full color sensor AM 3302) as photodetector. Dyes extracted from spinach leaves were analyzed. AM 3302 has three color (red, green and blue) filters in front of the face of the photo-sensor, and transduces photo-intensities to the voltages. Three voltage outputs are taken into the microprocessor by the rapid sampling method. Three outputs, which correspond to the light intensity at three different wavelengths, form the three point spectrum. AM 3302 can be used as a simple detector of the hue. Extracted dyes from spinach leaves were separated on the silica gel column. The green and two yellow fractions were monitored by the hue detector. The green fraction was fractionated and its fast atom bombardment mass (FAB-MS) spectrum was measured and identified to be chlorophyll a by quasi molecular ion m/z 893 [M+H]+ value.

Identification of Na+,K+-ATPase inhibitors of volume-expanded hog plasma.

Na+,K+-adenosine triphosphatase (ATPase) inhibitors possessing inhibitory activities against the specific binding of ouabain to Na+,K+-ATPase and 86Rb uptake into hog erythrocytes have been purified from the plasma of hog acutely infused with saline. The purifications were performed by a combination of Amberlite XAD-2 adsorption chromatography and several steps of high performance liquid chromatography using four different types of columns. Inhibitors purified to homogeneity were identified as linoleic and oleic acids, gamma-stearoyllysophosphatidylcholine, gamma-arachidoyllysophosphatidylcholine, gamma-linoleoyllysophosphatidylcholine, and gamma-oleoyllysophosphatidylcholine. Small amounts of beta-arachidoyllysophosphatidylcholine, gamma-docosapentaenoyllysophosphatidylcholine, gamma-eicosatrienoyllysophosphatidylcholine, and gamma-palmitoyllysophosphatidylcholine were also detected by both fast atom bombardment mass and proton nuclear magnetic resonance spectrometric studies. Only gamma-acyllysophosphatidylcholines showed inhibitory activities on Na+,K+-ATPase and ouabain-binding activities. These lysophosphatidylcholines and unsaturated free fatty acids were effective at 100 microM levels in attaining 50% inhibition of the enzyme activity. The ouabain-displacing activity in plasma caused by these compounds increased with time during saline infusion. The maximal plasma levels of these components were approximately 10 times higher than that in the preinfusion plasma sample.

Identification of the ions produced by fast atom bombardment mass spectrometry in some polyesters and polyamides

Fast atom bombardment (FAB) mass spectrometry was applied to the analysis of two polyesters, poly(ethylene adipate) and poly(epsilon-caprolactone), and two polyamides, Nylon 6.6 and Nylon 6. The peaks present in the spectra of the crude polymers were identified as corresponding to protonated molecular ions of preformed cyclic oligomers and of low molecular weight compounds contained in the polymer samples; these species were desorbed intact from the glycerol matrix under FAB conditions. When the polymers investigated were accurately purified from low molecular weight compounds, no significant peaks were observed in their FAB mass spectra. Instead, the FAB mass spectra of the mixtures extracted from the polymers were found to be very similar to those obtained for crude polymers.

Studies on the mass spectrometry of natural products: V. Negative ion fast atom bombardment and collisional activation mass spectrometry in the structural analysis of oligoglycosides

The negative ion fast atom bombardment (NFAB) mass spectrometry of eight glycosides containing one to three sugar units have been studied. The mass spectra of NFAB exhibit more predominant quasi-molecular ions without adduct ions in the high mass region, which indicate more unambiguously the molecular weights of the glycosides, than the positive ion FAB (PFAB) spectra do. Among the three matrix substances tested, glycerol, thioglycerol and PEG-200, the last one was found to give the best results. The characteristic ions of NFAB collisional activation (NFAB-CA) spectra of [M-H]− ions were more abundant and gave more definite information about sequences of the sugar units than the corresponding PFAB-CA spectra of [M + H]+ ions.