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T Yamagaki

Publications and source records attributed to T Yamagaki.

15 recordsLinked to original sources
PubMed2001

Ion intensity analysis of post-source decay fragmentation in curved-field reflectron matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of carbohydrates: for structural characterization of glycosylation in proteome analysis.

The various kinds of oligosaccharides were analyzed by using post-source decay (PSD) fragmentation method of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Since the curved field reflectron MALDI-MS can record all fragment ions in a single measurement, we can discuss the fragment ion intensity in PSD mass spectrum more accurately. The intensities of the PSD fragment ions indicate the fine structure of the saccharide chains. The type of glycosyl linkages could be determined by the ion intensity analysis, and the stereo isomers of monosaccharides were distinguished by the MALDI-PSD fragment ion analysis. The linkage isomers and structural isomers were also distinguished by this method. The ion intensity analysis of curved-field reflectron MALDI-MS could be a powerful tool for glycosylation analysis.

Carbohydrate Conformation↗
PubMed2001

Distinguishing of linkage isomers of lactotetra oligosaccharides by using the relative ion intensity analysis of post-source decay fragment ions in curved-field reflectron matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The native oligosaccharides of lacto-N-neotetraose (Gal beta1-4GlcNAc beta1-3Gal beta1-4Glc; LNnT) and lacto-N-tetraose (Gal beta1-3GlcNAc beta1-3Gal beta1-4Glc; LNT) were analyzed by using curved-field reflectron matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Since a curved-field reflectron TOFMS enables a simultaneous focusing of a wide mass range of metastable fragment ions, the relative ion intensities in the post-source decay (PSD) mass spectra can be discussed. The PSD mass spectra of LNnT and LNT were distinguishable in their relative ion intensities. In the case of LNT, beta-elimination could occur in the N-acetyl glucosamine (GlcNAc) at the C-3 position, which was bonded by galactose (Gal); however, it did not occur in LNnT. The 3-O elimination caused a difference in the relative ion intensities in the PSD mass spectra of LNnT and LNT. The beta1-3 glycosyl linkage cleaved more easily than the beta1-4 glycosyl linkage in the MALDI-PSD fragmentation. An analysis of the relative ion intensities in the MALDI-PSD mass spectra of oligosaccharides was very useful for distinguishing the linkage isomers and for characterizing the types of glycosyl linkages.

Carbohydrate Sequence↗
PubMed2000

Fluorescent modification for peptide sequencing by postsource decay-matrix assisted laser desorption/ionization-mass spectrometry.

The sequential analysis of a peptide of CDYEGRLI, relating to the nucleic proteins in influenza virus, was performed by the postsource decay (PSD) fragmentation method using matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). The sequence of the peptide was difficult to analyze by MALDI-MS since the PSD fragment ions of the peptide were almost never observed and were not amenable to complete sequence interpretation. The peptide was modified by 4(5)-(iodoacetamide) fluorescent reagent to improve the sensitivity of the MALDI-PSD fragment spectrum. In the spectrum of the fluorescent modified peptide, almost all sequential b-series fragment ions were observed clearly, which was sufficient for complete sequence interpretation. The results indicate the advantage of fluorescent modification for the total sequencing of the peptides by MALDI-MS.

Fluoresceins↗
PubMed2000

Post-source decay fragmentation analyses of linkage isomers of Lewis-type oligosaccharides in curved-field reflectron matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: combined in-source decay/post-source decay experiments and relative ion abundance analysis.

Linkage isomers of Lewis(X) trisaccharide (Le(X)) and Lewis(a) trisaccharide (Le(a)) were distinguished by the post-source decay (PSD) fragment spectra obtained by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) without permethylation. Both Y- and Z-type fragmentations were observed at the C-3 position of N-acetylhexosamine. beta-Elimination at C-3 of the reducing-end N-acetylglucosamine in Le(X) formed a double bond, which conjugated to an N-acetyl group, making the chemical species stable. In contrast, the double bond formed in the reducing end glucose of 3-fucosyllactose was unstable owing to the lack of a conjugated system. Therefore, beta-elimination of N-acetylglucosamine occurred predominantly rather than that of hexose in MALDI-PSD fragmentation. The measurements of the PSD fragment mass spectra using pseudo precursor ions originating from in-source decay were useful for the analyses of the fragmentation mechanisms and for the assignments of the chemical species of the fragment ions. The combined in-source decay/post-source decay experiments revealed the formation of a double bond between C-2 and C-3 in N-acetylglucosamine of Le(X). Abundance analysis of the PSD ions indicated that the 1-3 glycosyl linkage cleaves more easily than does the 1-4 linkage in MALDI-PSD fragmentation. Ion abundance analyses were useful in estimating the degree of Y- and Z-type fragmentation at the C-3 position of hexose and N-acetylhexosamine. The analysis of the relative ion abundances was a powerful tool for the assignments of the chemical species of the PSD ions.

Carbohydrate Conformation↗
PubMed1999

Influence of acceleration voltages on relative ion intensities in the post-source decay fragmentation of isomeric cyclic oligosaccharides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The isomeric sugar-branched cyclodextrin (CD) derivatives of 6-O-glucosyl-betaCD (G1-betaCD) and 6,6-di-O-glucosyl-alphaCD (G1, G1-alphaCD) were analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry at the different acceleration voltages of 20 and 8 kV. In the post-source decay (PSD) fragment spectra of G1-betaCD and G1, G1-alphaCD under the reduced acceleration voltage 8 kV, the relative intensity ratios of one-site cleavage ions [M - G1](+) to two-site cleavage ions [M - G2 approximately 5](+) were much larger than at 20 kV. This change in the intensity ratio in the spectra of G1, G1-alphaCD was much larger than in the spectra of G1-betaCD. The measurements under the reduced acceleration voltage were useful to distinguish easily between the otherwise very similar PSD fragment spectra of G1-betaCD and G1, G1-alphaCD. It was concluded that the acceleration energy is one of the most effective parameters controlling relative ion intensities in PSD, and that distinction between these oligosaccharide isomers is facilitated by manipulation of this parameter.

Carbohydrate Sequence↗
PubMed1999

A new technique distinguishing alpha2-3 sialyl linkage from alpha2-6 linkage in sialyllactoses and sialyl-N-acetyllactosamines by post-source decay fragmentation method of MALDI-TOF mass spectrometry.

Alpha2-3 and alpha2-6 sialyl linkage types of sialyllactoses and sialyl-N-acetyllactosamines were analyzed by post-source decay (PSD) fragmentation method using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. A new matrix of norharmane was suited for the MALDI-TOF measurements of sialyl oligosaccharides. The fragment ions B1 produced by the cleavage of alpha2-3 sialyl linkages indicate much higher intensity than those produced by the cleavage of alpha2-6 sialyl linkages in sialyllactoses and sialyl-N-acetyllactosamines. Thus, alpha2-3 sialyl linkages cleave much easier than alpha2-6 sialyl linkages in MALDI-PSD fragmentation method. These results suggest that the new techniques using PSD fragmentation of MALDI-TOF mass spectrometry enables us to distinguish alpha2-3 sialyl linkage from alpha2-6 linkage in sialyl oligosaccharides.

Amino Sugars↗
PubMed1998

Influence of different glycosidic linkages on relative ion intensities in post-source decay fragmentation of a xyloglucan heptaoligosaccharide using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Post-source decay fragment analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) has been applied to a highly branched xyloglucan heptasaccharide from tamarind seed. All fragment ions were produced by cleavage of the glycosidic linkages, including multi-site cleavages. The relative intensities of fragment ions that originated from one-site cleavages of the glycosidic linkages were much higher than those arising from two-site cleavages of the same kind of glycosidic linkage, which were in turn higher than those from three-site cleavages. The types of glycosidic linkages were an important factor which influenced the relative intensities of the MALDI-PSD (post-source decay) fragment ions. In the MALDI-PSD fragment spectrum of the xyloglucan heptasaccharide, the relative intensities of the ions produced by the cleavage of an alpha 1-6 glycosidic linkage were much higher than those arising from cleavage of the beta 1-4 glycosidic linkage.

Carbohydrate Sequence↗
PubMed1998

Influence of stereoisomeric glucose, galactose and mannose residues on fragmentation at their glycosidic linkages in post-source decay fragment analyses for oligosaccharides using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The isomeric sugar branched beta-cyclodextrin (CD) derivatives (Glc-beta CD, Gal-beta CD, and Man-beta CD) were analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. In the MALDI post-source decay (PSD) fragmentation of Glc-beta CD, Gal-beta CD and Man-beta CD, the fragment ions of [M-Glc]+, [M-Gal]+ and [M-Man]+ were produced by the one-site cleavage of the alpha 1-6 glycosidic linkage at the branch (Y-type fragmentation). The abundances of [M-Gal]+ ions were much higher than that of [M-Man]+. These results indicated that Glc-beta CD and Gal-beta CD were distinguishable from Man-beta CD and that Y-type fragmentations of the branched glycosidic linkage at the glycosyl donors of alpha-D-Glc and alpha-D-Gal were more predominant than that at the glycosyl donor of alpha-D-Man by MALDI-PSD fragment analysis. It was concluded that the abundances of PSD fragment ions depended on the stereochemistry of the glycosyl donors in the cleavage of the glycosidic linkage of the oligosaccharides in MALDI-TOF mass spectra.

Carbohydrate Sequence↗
PubMed1998

Structural analysis of xyloglucan oligosaccharides by the post-source decay fragmentation method of MALDI-TOF mass spectrometry: influence of the degree of substitution by branched galactose, xylose, and fucose on the fragment ion intensities.

Highly branched xyloglucan oligosaccharides were analyzed by the post-source decay (PSD) fragmentation method of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The ratio of [M-Xyl]+ and [M-Gal]+ fragment ion intensities could be used to characterize the degree of Gal substitution at the non-reducing end, because the number of possible chemical species was directly related to their relative ion intensity. The intensity of the [M-Fuc]+ ion was predominantly strong in the fragment spectrum of fucosyl oligosaccharides as the first fragmentation, indicating the fucosyl linkage to be much weaker than the other glycosidic linkages in the MALDI-PSD fragmentation. Setting fragment ion [M-Fuc]+ to the pseudo precursor ion [MF]+, the second fragmentation ions were produced from [MF]+ in the drift region in PSD fragmentation of fucosyl oligosaccharides.

Fucose↗
PubMed1997

The conformation formed by the domain after alanine-155 induces inversion of aspartic acid-151 in alpha A-crystallin from aged human lenses.

A new cleavage site, which is a post-translational modification, was found between residues His-154 and Ala-155 in alpha A-crystallin from the aged human lens. After trypsin digestion of alpha A-crystallin two peptides that include Asp-151 were obtained and have remarkable differences. That is, the stereo-configuration of the Asp-151 in the normal length peptide was predominately inverted to the D-isomer of beta-aspartyl form (D/L of 5.7). However, the stereoconfiguration of the Asp-151 in the cleavage peptide, that lacks the sequence following Ala-155 to the C-terminus, remained predominately in the L-isomer form as indicated by a D/L value of 0.3. The results suggest that the secondary structure in the region of Ala-155 to the C-terminus may constitute a field that causes the inversion of the Asp-151 to the D-isomer form. Since this kind of cleavage was not found in alpha A-crystallin from young lens, the cleavage between His-154 and Ala-155 is probably the result of aging.

Aged↗
PubMed1997

Analysis of glycosidic linkages in saccharide compounds by post-source decay fragment methods in matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy.

Maltotriosyl- and panosyl-alpha-cyclodextrins and the nonaose of pullulan were analyzed by post-source decay (PSD) fragment methods of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy. By the mass number analysis, it was found that all of the PSD fragment ions were produced by cleavages of glycosidic linkages. Comparison of the relative intensities of the ions in those compounds enabled us to distinguish two kinds of glycosidic linkages, alpha 1-4 and alpha 1-6, by MALDI-TOFMS with a new type of ion reflector: the curved field reflectron.

Carbohydrate Sequence↗
PubMed1997

NMR spectroscopic analysis of sulfated beta-1,3-xylan and sulfation stereochemistry.

A novel sulfated beta-1,3-xylan product was synthesized from algal cell wall microfibril homoxylan by the N,N-dimethylformamide (DMF)-SO3 complex sulfation method. Antithrombin activity appeared in this product was 6.5 times higher than that of standard heparin. From the results of 1H- and 13C-NMR spectroscopic analyses by DQF-COSY and HMQC and an infrared spectroscopic analysis, it was revealed that the ordered structure of beta-1,3-xylan as a triple helix had decayed and the resulting conformational changes had been caused by the sulfation reaction. The sulfated positions on the C-4 hydroxyl groups of the xylose residues were determined from 13C-NMR chemical shifts, and it was found that regioselective sulfation had occurred predominantly with the C-4 secondary hydroxyl groups to produce a mono-substituent. Another type of sulfation of beta-1,4-xylan that showed no regioselectivity is considered to have been due to the different conformation of both xylans chains such as the triple helix in beta-1,3-xylan and the double straight chain like cellulose in beta-1,4-xylan. Therefore, the different type of regioselective sulfation of beta-1,3- and beta-1,4-xylan was caused by the difference in steric hindrance due to these conformations. These different types of regioselective sulfation with different linkage positions are also discussed for the secondary hydroxyl groups in beta-1,3- and beta-1,4-glucan after chemoselective sulfation of the C-6 primary hydroxyl groups.

Antithrombins↗
PubMed1997

Structural analyses of xyloglucan heptasaccharide by the post-source decay fragment method using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

In the post-source decay (PSD) fragment spectrum of a reduced xyloglucan heptasaccharide (XXXGol) from tamarind seeds, eleven sodium-adduct fragment ions and a precursor ion [M + Na]+ were clearly observed by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Each fragment ion interval corresponded to the absence of unhydroxylose, unhydroglucose, and glucitol residues, indicating that PSD fragmentation cleavage in the sugar compound occurred only at glycosidic linkages close to the oxygen atom of saccharide ring members, and not in inner sugar ring bonds. The PSD fragment ions were classified into two series, one involving the reducing end and the other involving the non-reducing end. Structural information from both the reducing and non-reducing ends could therefore be simultaneously obtained from the measurement of the positive ion mode. Almost all the fragment ions from species larger than trisaccharide residues could be detected in this PSD fragment experiment. Such fragmentation information will enable the structural determination of xyloglucan oligosaccharides.

Carbohydrate Sequence↗
PubMed1996

Post-source decay fragment spectra of cyclomalto-octaose and branched cyclomalto-hexaose by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

gamma-Cyclodextrin, maltosyl-alpha-cyclodextrin and diglucosyl-alpha-cyclodextrin were analyzed using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. All of these compounds have the same molecular weight (M.W. = 1297.15) and consist of only D-glucopyranose. From a comparison of the intensities in the post-source decay (PSD) fragment spectra of these cyclodextrin derivatives, correlation between the chemical structures and the relative intensities in the PSD fragment ions was found. The correlation is considered to be caused by the difference in the number of cleavage sites at the glycosyl binding. It was found that the intensity of the PSD ion resulting from one cleavage is higher than that resulting from two cleavages at a glycosyl bond. The results show that PSD fragment-ion spectrum method used in MALDI-TOF mass spectrometry is a very powerful technique for the structural analyses of the sugar-substituted cyclodextrins.

Carbohydrate Sequence↗