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The information that regulates the way in which cells recognize and respond to their neighbors resides at the area of contact between cells, in particular, in the molecular structures present at the cell surface. Complex carbohydrates are major components of the cell surface and are found conjugated as glycoproteins and glycolipids. Oligosaccharides differ in structure between cells, are involved in intercellular recognition processes during development, and are known to be modified in metastatic cancer cells. My laboratory focuses on an understanding of the enzymes that synthesize cell surface carbohydrates, the glycosyltransferases. In addition, characterization of the carbohydrate structures themselves and development of new methods for elucidation of these molecules is ongoing.
This includes new methods in higher-dimensional nuclear magnetic resonance (NMR) spectroscopy and fundamental studies in fragmentation of carbohydrate molecules by mass spectrometry, with the overall goal being to assign the detailed structures of these complex molecules unambiguously.
The glycosyltransferases in mammals are a large family of enzymes (over 100) localized primarily to the Golgi apparatus, which transfer in assembly-line fashion a series of monosaccharides to a growing oligosaccharide chain. My laboratory is interested in a series of glycosyltransferases involved in synthesis and branching of novel core structures of glycoprotein oligosaccharides, and in coming to understand the control of expression and role of these enzymes in different tissues.
For structural elucidation of glycoprotein oligosaccharides, we employ high-field NMR, mass spectrometry, and gas chromatography-mass spectrometry, in addition to specific methods of chemical degradation which are topics of research in the lab. Recent work has dealt with developments of gas-phase methods for separation and differentiation of oligosaccharide isomers.
Fang T.T., Bendiak, B. The stereochemical dependence of unimolecular dissociation of monosaccharide-glycolaldehyde anions in the gas phase: A basis for assignment of the stereochemistry and anomeric configuration of monosaccharides in oligosaccharides by mass spectrometry via a key discriminatory product ion of disaccharide fragmentation, m/z 221 Journal of the American Chemical Society, 2007 129:9721-9736
Armstrong, G.S., Mandelshtam, V.A., Shaka, A.J., Bendiak, B. Rapid high-resolution four-dimensional NMR spectroscopy using the filter diagonalization method and its advantages for detailed structural elucidation of oligosaccharides. Journal of Magnetic Resonance, 2005, 173: 160-168.
Dwivedi, P., Bendiak, B., Clowers, B.H., Hill, H.H. Rapid resolution of carbohydrate isomers by electrospray ionization ambient pressure ion mobility spectrometry-time-of-flight mass spectrometry (ESI-APIMS-TOFMS). Journal of the American Society for Mass spectrometry, 2007, 18: 1163-1175.
Polfer, N.C., Valle, J.J., Moore, D.T., Oomens, J. Eyler, J., Bendiak, B. Differentiation of isomers by wavelength-tunable infrared multiple-photon dissociation-mass spectrometry: application to glucose-containing disaccharides. Analytical Chemistry, 2006, 78: 670-679.
Armstrong, G.S., Bendiak, B. High-resolution four-dimensional carbon-correlated 1H-1H ROESY experiments employing isotags and the filter diagonalization method for effective assignment of glycosidic linkages in oligosaccharides. Journal of Magnetic Resonance, 2006, 181: 79-88.
Bendiak, B. Sensitive through-space dipolar correlations between nuclei of small organic molecules by partial alignment in a deuterated liquid solvent. Journal of the American Chemical Society, 2002, 124: 14862-14863.
Martensson S, Levery SB, Fang TT, Bendiak B. Neutral core oligosaccharides of bovine submaxillary mucin--use of lead tetraacetate in the cold for establishing branch positions. Eur J Biochem. 1998: 258: 603-622.
D’Agostaro, G.A.F., Zingoni, A., Moritz, R.L., Simpson, R.J., Schachter, H., Bendiak, B. Molecular cloning and expression of cDNA encoding the rate UDP-N-acetylglucosamine:a-6-D-mannoside b-1,2-N-acetylglucosaminyltransferase II. Journal of Biological Chemistry, 1995, 270: 15211-15221.
Bendiak, B., Salyan, M.E., Pantoja, M. Sequential Removal of monosaccharides from the reducing end of oligosaccharides. 2. Fundamental studies of a reaction between hydrazine compounds and sugars having a glycosyl moiety on a carbon atom adjacent to a carbonyl group. Journal of Organic Chemistry, 1995, 60: 8245-8256.
Cumming, D.A., Hellerqvist, C.G., Harris-Brandts, M., Michnick, S.W., Carver, J.P., Bendiak, B. Structures of asparagines-linked oligosaccharides of the glycoprotein fetuin having sialic acid linked to N-acetylglucosamine. Biochemistry, 1989, 28: 6500-6512.
Bendiak, B., Schachter, H. Control of Glycoprotein Synthesis: Purification of UDP-N-acetylglucosamine:a-D-mannoside b1-2 N-acetylglucosaminyltransferase II from rat liver. Journal of Biological Chemistry, 1987, 262: 5775-5783.