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Anomeric Configuration (anomeric + configuration)
Selected AbstractsAdvances on the compositional analysis of glycosphingolipids combining thin-layer chromatography with mass spectrometryMASS SPECTROMETRY REVIEWS, Issue 3 2010Johannes Müthing Abstract Glycosphingolipids (GSLs), composed of a hydrophilic carbohydrate chain and a lipophilic ceramide anchor, play pivotal roles in countless biological processes, including infectious diseases and the development of cancer. Knowledge of the number and sequence of monosaccharides and their anomeric configuration and linkage type, which make up the principal items of the glyco code of biologically active carbohydrate chains, is essential for exploring the function of GSLs. As part of the investigation of the vertebrate glycome, GSL analysis is undergoing rapid expansion owing to the application of novel biochemical and biophysical technologies. Mass spectrometry (MS) takes part in the network of collaborations to further unravel structural and functional aspects within the fascinating world of GSLs with the ultimate aim to better define their role in human health and disease. However, a single-method analytical MS technique without supporting tools is limited yielding only partial structural information. Because of its superior resolving power, robustness, and easy handling, high-performance thin-layer chromatography (TLC) is widely used as an invaluable tool in GSL analysis. The intention of this review is to give an insight into current advances obtained by coupling supplementary techniques such as TLC and mass spectrometry. A retrospective view of the development of this concept and the recent improvements by merging (1) TLC separation of GSLs, (2) their detection with oligosaccharide-specific proteins, and (3) in situ MS analysis of protein-detected GSLs directly on the TLC plate, are provided. The procedure works on a nanogram scale and was successfully applied to the identification of cancer-associated GSLs in several types of human tumors. The combination of these two supplementary techniques opens new doors by delivering specific structural information of trace quantities of GSLs with only limited investment in sample preparation. © 2009 Wiley Periodicals, Inc. Mass Spec Rev 29:425-479, 2010 [source] Characterization of a new serotype g isolate of Aggregatibacter actinomycetemcomitansMOLECULAR ORAL MICROBIOLOGY, Issue 3 2010K. Takada Summary Aggregatibacter actinomycetemcomitans is usually isolated from the oral cavity where it is associated with active periodontitis. The species can be divided into six serotypes (a,f) according to their surface carbohydrate antigens. However, some clinical isolates cannot be grouped within these six serotypes. Gram-negative, facultative anaerobic, catalase-positive coccobacilli were isolated from a patient with periodontitis and identified by employing genetic, biochemical and serological analyses. Phenotypic data identified the isolate as A. actinomycetemcomitans. Serotype-specific polysaccharide antigen from the isolate was untypeable by immunodiffusion testing in comparison with reference A. actinomycetemcomitans serotype a to f strains. Biofilm formation by the isolate was strong but cytotoxic activity was low. Gas chromatography/mass spectroscopy analysis of partially methylated alditol acetates from surface polysaccharide showed the presence of 2,4-di- O -methyl-rhamnose and 2,3,6-tri- O -methyl-glucose, with a 1 : 1 m ratio. The 1H- and 13C-nuclear magnetic resonance spectra of the antigen showed that both constituent glycoses had ,-anomeric configuration. It is proposed that the untyped strain is a new A. actinomycetemcomitans serotype, designated serotype g. [source] Rapid differentiation of isobaric and positional isomers of structurally related glycosides from Phytolacca bogotensisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2009Guillermo Montoya Through the action of glycosyltransferases, a plant can biosynthetically assemble small different aglycons or 'templates' to various polysaccharides to produce numerous glycoconjugates differing in the type of the attached aglycon, the anomeric configuration of C-1 of the glycosylating sugar, the type of sugar and the different position of attachments of the sugar unit present in the polysaccharide chain. The position of attachments and the anomeric configuration of the different sugar present in the polysaccharide create the opportunity to generate molecules with either the same or very close molecular weights, which have relative structural similarity , forming isobaric and positional isomers. Although isomeric differentiation was once considered outside of the domain of mass spectrometry, this task can now be resolved using tandem mass spectrometry. In a standardized purified glycoconjugate fraction (SPT01) from Phytolacca bogotensis, we report conventional electrospray ionization mass spectrometry and collision-induced dissociation (CID) MS/MS parameters which favored the formation of characteristic product ions. This allowed us to suggest the type of sugar linkages present in a specific glycoconjugate. Ten new glycoconjugate are described from this plant and another twelve known saponins were structurally characterized using the automatic MSn acquisition mode. The differentiation of two pairs of positional isomers and four isobaric glycosides and the production of a library of 30 glycosides present in P. bogotensis were accomplished. Copyright © 2009 John Wiley & Sons, Ltd. [source] Application of NMR, molecular simulation, and hydrodynamics to conformational analysis of trisaccharides,BIOPOLYMERS, Issue 4 2003Ann M. Dixon Abstract The preferred conformations and conformational flexibilities of the trisaccharides ,-D-Glcp -(1,2)-,-D-Glcp -(1,3)-,-D-Glcp -OMe (I) and ,-D-Glcp -(1,3)[,-D-Glcp -(1,4)]-,-D-Glcp -OMe (II) in aqueous solution were determined using nuclear magnetic resonance (NMR) spectroscopy, molecular dynamics (MD) and Langevin dynamics (LD) simulations, and hydrodynamics calculations. Both trisaccharides have a vicinal substitution pattern in which long range (nonsequential) interactions may play an important role. LD simulation at 600 K indicated that the all- syn conformation predominated, though other conformations were apparent. NOE data and MD and LD simulations at 298 K all indicated that trisaccharide I is a single all- syn conformer in solution. Given that previous studies showed evidence of anti -conformers in ,-D-Glcp -(1,2)-,-D-Glcp -(1,3)-,-D-Glcp -OMe, this result provides an example of how changing the anomeric configuration of one residue from , to , can make an oligosaccharide more rigid. Discrepancies in inter-ring distances obtained by experiment and by simulation of the all- syn conformer suggest the presence of an anti -, conformation at the ,-(1,4)-linkage for II. A combined analysis of measured and calculated translational diffusion constants and 13C T1 relaxation times yield order parameters of 0.9 for each trisaccharide. This implies that any interconversion among conformations is significantly slower than tumbling. Anisotropies of approximately 1.6 and 1.3 calculated for I and II, respectively, are consistent with the observed relatively flat T1 profiles because the tumbling is not in the motional narrowing regime. Published 2003 Wiley Periodicals, Inc. Biopolymers 69: 448,460, 2003 [source] Circular dichroism as a reliable tool for anomeric assignment of glycosyl-2-phenyl-2H- 1,2,3-triazole C -nucleoside analogs.CHIRALITY, Issue 10 2006A rule for prediction of their anomeric configuration Abstract The circular dichroism (CD) of a series of acyclic C -nucleoside analogs; 4-(pentahydroxypentyl-1-yl)-2-phenyl-2H -1,2,3-triazoles [1,5] and 4-(D - glycero - D - gulo)-2-phenyl-2H -1,2,3-triazole 6, are reported. A correlation between the sign of the Cotton effect at the maximal UV absorption and the absolute configuration of the carbon atom ,- to the triazole base moiety is reported. The CD of anomeric 4-(,,,- D -arabinofuranosyl)- and 4-(,,,- D -arabinopyranosyl)-2-phenyl-2H -1,2,3-triazole C -nucleosides are reported. The assignment of the anomeric configuration of C -glycosyl-2-phenyl-2H -1,2,3-triazoles from their CD spectra was found to be a simple method that relies on comparison of the sign of the Cotton effect at the maximal UV absorption and the absolute configuration of the anomeric carbon atom. A correlation between the anomeric configuration and the sign of the Cotton effect at the maximal UV absorption is deduced and generalized as a rule for prediction of the anomeric configuration of C -glycosyl-2-phenyl-2H -1,2,3-triazoles. Nuclear Overhauser effect and 13C NMR spectra supported the CD assignment rule. Chirality, 2006. © 2006 Wiley-Liss, Inc [source] | ||||||||||