巻号一覧
46 巻, 1 号
選択された号の論文の13件中1～13を表示しています
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David A. LIGHTNER, Frank S. STEINBERG, Laurence D. HUESTIS1998 年 46 巻 1 号 p. 11-16
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーIn the electron impact mass spectra of a series of cycloalkylacetones with ring sizes varying from cyclopropane to cycloheptane, the intensity of the McLafferty rearrangement ion at m/z 58 increases with the larger, less strained rings. The larger ring ketones give surprisingly intense “McLafferty plus one” ions at m/z 59, which is the base peak in the mass spectrum of cyclohexylacetone. This double hydrogen McLafferty rearrangement is favored over the single hydrogen rearrangement at both high (70 eV) and low (14 eV) ionizing voltages. Deuterium labelling confirms the expected considerable hydrogen migration in the cycloalkyl ring, occurring following hydrogen transfer to the carbonyl oxygen and prior to C-C bond cleavage.抄録全体を表示PDF形式でダウンロード (582K) -
Stéphane MABIC, Neal CASTAGNOLI Jr.1998 年 46 巻 1 号 p. 17-24
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーThe EI mass spectra of 1,4-disubstituted-1,2,3,6-tetrahydropyridinyl derivatives were studied using ten regioselectively labeled isomers of the neurotoxin MPTP. Analysis of the isotopically enriched ions obtained from each labeled analog allowed us to identify the origins of the fragments. Fragmentation pathways are proposed that account for the formation of most of the major peaks. Based on the fragment ions detected and the calculated HOMO energies, it is proposed that electron bombardment results in a resonance delocalized radical cation that could be derived from initial electron loss from the nitrogen atom or the olefinic double bond.抄録全体を表示PDF形式でダウンロード (693K) -
Mitsuo TAKAYAMA1998 年 46 巻 1 号 p. 33-36
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーThe ionization efficiency under fast atom bombardment conditions with liquid matrix have been studied. The dependence of fast atoms, Xe, Ar, and He, for the ionization efficiency from the surface of matrix solution bombarded with 6 keV atom beams has been rationalized from the standpoint of elastic/inelastic collisions between a fast atom and a matrix molecule in the surface layer. A relationship between ionization efficiency and atomic mass, which was formulated by a collision theory, predicted a tendency that the efficiency approaches asymptotically to a finite value with increasing atomic mass. The curves for the ionization efficiency versus atomic mass, obtained by using a few compounds, were in agreement with the theoretical prediction in the tendency.抄録全体を表示PDF形式でダウンロード (389K) -
Toshikazu HIRAKI, Masayuki KUBOTA, Takashi HIRANO, Haruki NIWA, Mamoru ...1998 年 46 巻 1 号 p. 37-43
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーPositive and negative ion fast atom bombardment tandem mass spectrometry (FAB-CID MS/MS) has established the fragmentation pattern of the 18 imidazolone derivatives which are related to the structure of the GFP (green fluorescent protein) chromophore in the jellyfish Aequorea bioluminescence. Ring cleavage of the C5-N1 and C2-N3 bonds is characteristics of these compounds, but for NH derivatives cleavage of the methylidene group as well as the C4-C5 and C2-N3 bonds also occurred in the positive ion mode, while ring cleavage of the C2-N3 and C4-C5 bonds occurred commonly in the negative ion mode. On the basis of the CID-MS/MS (collision induced dissociation tandem mass spectrometry) the structures of protonated molecules produced upon FAB are discussed.
When the structure of the fragment ion has a p-quinonoid moiety, distinct peaks due to radical anion species such as [M-H-CH3]-· are observed in their CID-MS/MS of parent anions [M-H]-, which seems to be characteristics of the conjugated p-hydroxyphenyl structures.抄録全体を表示PDF形式でダウンロード (544K) -
Yoko OHASHI, Tadashi II, Masayuki KUBOTA, Shigeki NUNOMURA, Haruki NIW ...1998 年 46 巻 1 号 p. 45-52
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーHere we report that FAB CID-MS/MS, choosing an ion originating from the in-source degradation prior to the full acceleration of the molecule-related ion as the precursor, is an excellent means to differentiate linkage isomers. FAB CID-MS/MS performed in this way results in a product ion spectrum, which is enriched with the fragmentation information, and which may thus indicate the position of the newly formed OH group already produced in the ion source. Linkage knowledge may be classified into one of three categories as described later. This method was applied to acidic Lewis-type glycoconjugates —putative ligands for selectins [L. L. W. Cooling, D.-S. Zhang, and T. A. W. Koerner, Trends in Glycosci. Glycotech., 9, 191 (1997)]— and their neutral analogs to differentiate linkage isomers by mass spectrometry. With these glycoconjugates FAB CID-MS/MS having [M+H]+s as the precursor ions is a good means to distinguish the linkage isomers only in simple cases, but not in general cases. By using ions originating from in-source degradation prior to the full acceleration of the molecule-related ion as the precursor, we were able to differentiate between Lea and Lex.抄録全体を表示PDF形式でダウンロード (662K) -
M. ONGENA, Ph. JACQUES, G. van VYNCHT, P. CHARLIER, E. de PAUW, Ph. TH ...1998 年 46 巻 1 号 p. 53-56
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーPyoverdins are chromopeptides produced by the so-called fluorescent group of the bacterial genus Pseudomonas. Species or even strain specific they differ in the composition of their peptide chains. For classification purposes it is of importance to get fast information regarding the nature of the latter. For two new representatives from hydrolysis results and especially from an analysis of the data obtained from electrospray ionization (ESI) and fast atom bombardement (FAB) mass spectrometry measurements the amino acid sequences can be suggested as Asp-BuOHOrn-Dab-aThr-Gly-Ser-Ser-OHAsp-aThr (Pseudomonas putida BTP16) and Ser-Ser-FoOHOrn-Ser-Ser-Ser-FoOHOrn-Lys-Lys (Pseudomonas fluorescens BTP7).抄録全体を表示PDF形式でダウンロード (403K) -
杉 和人, 井津 源市, 橋本 豊1998 年 46 巻 1 号 p. 57-62
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーPolar derivatization method for electrospray ionization (ESI) was developed and applied to the sensitive analysis of nonpolar ketosteroid in plasma. 4-Androstene-3,17-dione (androstenedione) in human plasma was purified by solid-phase extraction with Bond Elut C18 and derivatized to the carboxymethyloxime form (androstenedioxime) as a polar derivative. Androstenedione-d6 as an internal standard was synthesized and its deuterium contents were satisfactory for the sensitive analysis of androstenedione. The LC/ESI-MS condition for androstenedioxime was performed and single peak was obtained without separation of four steric isomers. Sensitivity of androstenedioxime in this mehtod was enhanced 5 times higher than androstenedione. Calibration graphs were linear (r=0.999) from 2.5 to 100 ng/ml for androstenedione extracted from human plasma and inter-assay precision (RSD) was within 6%.抄録全体を表示PDF形式でダウンロード (410K) -
Hisao OKA, Yuko ITO, Sadaji YAMADA, Tadaaki KAGAMI, Junko HAYAKAWA, Ke ...1998 年 46 巻 1 号 p. 63-68
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーA reliable identification method for laccaic acids which are the main components in lac dye has been established using ESI LC/MS/MS with a volatile mobile phase containing acetylacetone. Addition of acetylacetone to the mobile phase enables us to separate laccaic acids without reduction of peak resolution. The volatile mobile phase, acetonitrile-0.05% aqueous TFA solution (1-4) containing 0.005 M acetylacetone, is applicable to directly interfaced ESI LC/MS/MS without clogging problems. In all ES tandem mass spectra of laccaic acids, [M-H-CO2]- and [M-H-2CO2]- appeared in considerable abundance, together with the weak ions of [M-H]-, [M-H-H2O]-, [M-H-CO2-H2O]-, and [M-H-2CO2-H2O]- when [M-H]- was selected as the precursor ion. Laccaic acids can be easily identified by these product ions. The method has been successfully applied to identification of laccaic acids in a jelly and in “Shi-kou,” which is a stick lac imported 1,200 years ago.抄録全体を表示PDF形式でダウンロード (482K) -
Thomas STAROSKE, Albert J. R. HECK, Peter J. DERRICK, Dudley H. WILLIA ...1998 年 46 巻 1 号 p. 69-73
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーNon-covalent complexes between the glycopeptide antibiotic vancomycin and the cell-wall precursor analog N-acetyl-D-Ala-D-Ala, as well as its deuterated enantiomer N-acetyl-L-Ala-L-Ala-d3 were probed using electrospray ionization mass spectrometry. In solution, the D,D-peptide interacts strongly with the antibiotic, whereas the L,L-peptide shows no observable complexation. Using a competition strategy, mass spectra were obtained from solutions containing vancomycin, N-acetyl-D-Ala-D-Ala, and N-acetyl-L-Ala-L-Ala-d3. With acetonitrile-water as the solvent, the ratio of free vancomycin to vancomycin complex was much higher than expected from solution interactions and the specific D,D-peptide complex and the non-specific L,L-peptide complex were detected in a 1.7 : 1 ratio. In contrast, sprayed from an ammonium acetate buffer solution both the amount and specificity of observed complex reflected solution interactions (only D,D-peptide complex was found). Thus, our results demonstrate that in electrospray mass spectrometry the conditions must carefully be chosen and control experiments must be carried out in order to exclude non-specific aggregation as a possible cause of complex formation.抄録全体を表示PDF形式でダウンロード (377K) -
Satoko AKASHI, Koji TAKIO1998 年 46 巻 1 号 p. 75-82
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーHydrogen/deuterium exchange (H/D) was performed on ubiquitin, cytochrome c and myoglobin, and deuterium incorporation was investigated by electrospray ionization mass spectrometry (ESIMS) under several conditions, with different pH and different content of organic solvent. Circular dichroism (CD) was employed to observe conformational changes in proteins under the conditions for H/D exchange and ESIMS measurements. Comparing the results of H/D exchange experiments, ubiquitin was found to be the most stable among the three proteins against acid and organic solvent. Cytochrome c seemed to have interconvertible conformers under acidic condition with the addition of acetonitrile, though it was not indicated in CD spectra. Myoglobin appeared to be folded very loosely in mildly acidic condition and it was difficult to observe its H/D exchange rate by ESIMS, though its CD spectra showed little change under the conditions used for ESIMS analyses. It was possible to investigate slight conformational changes in proteins by utilizing H/D exchange and ESIMS analyses complementary to CD spectra.抄録全体を表示PDF形式でダウンロード (842K) -
Kazuo HIRAYAMA, Reiko YUJI, Naoyuki YAMADA, Kazuyoshi NOGUCHI, Yoshiki ...1998 年 46 巻 1 号 p. 83-89
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーA new methodology using 2H-labeled leucine (Leu(D10)) was developed for peptide mapping of a large protein monoclonal immunoglobulin G2b (IgG2b). This method enabled easy assignment of molecular masses of digested peptides to an amino acid sequence of the original protein. It also enabled leucine and isoleucine residues to be distinguished from each other. Mouse 2H-labeled IgG2b (IgG2b(d)) was produced in the cells grown in a serum-free medium that contained Leu(D10) instead of Leu. The molecular mass of a peptide containing one leucine residue produced by the enzymatic digestion of RCM (reduced and carboxymethylated)-IgG2b(d) was 9 u larger than that of an unlabeled peptide. It was revealed that the number of leucine residues in the digested peptide was estimated easily by the mass difference between labeled and unlabeled peptides. Peptide mappings of RCM-IgG2b, RCM-IgG2b(d), and their equivalent mixture, RCM-IgG2b(mix), were obtained by digestion with lysyl-endopeptidase and consecutive MALDI-TOFMS analyses. It was easy to attribute the mass values to the peptides by the knowledge of the number of leucine residues, molecular masses of peptides and specificity of an enzyme. Leucine and isoleucine residues were easily distinguished in a protein when the protein contained 2H-labeled leucine residue.抄録全体を表示PDF形式でダウンロード (753K) -
Amina S. WOODS, D. P. LITTLE, Timothy CORNISH, R. J. COTTER, Daniel P. ...1998 年 46 巻 1 号 p. 91-96
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーPost-source decay (PSD) mass spectra of several peptides were obtained on a time-of-flight mass spectrometer with a curved-field reflectron to determine their amino acid sequences using very small quantities of sample. Peptides included angiotensin II, modified angiotensin II, and the tryptic fragments from somatostatin. Samples were prepared on the mass spectrometer probe using a piezo-electric micropipetting apparatus that enabled deposition of nanoliter volumes. The curved-field reflectron then enables recording of PSD mass spectra of mass-selected precursors without the need for stepping the reflectron voltage to bring different mass regions in focus. Using this instrument, sequence-specific ions could be observed with as little as a few atomoles of peptide.抄録全体を表示PDF形式でダウンロード (476K) -
Tao HE, Daniele FABRIS, Catherine FENSELAU1998 年 46 巻 1 号 p. 97-102
発行日: 1998年
公開日: 2007/07/20
ジャーナル フリーA study of the induction of metallothionein isoforms in human T24 bladder tumor cells revealed the presence of coeluting unknown proteins that were also heat stable and had molecular masses in the same range. In order to determine any relationship to metallothionein isoforms, these unknown proteins were identified, using database searching based on mass spectrometric determination of molecular weights, tryptic peptide mass maps and partial sequences. This study demonstrates that heat stable thymosin β-4 and β-10 are expressed in human bladder tumor cells.抄録全体を表示PDF形式でダウンロード (506K)
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