Synthesis and Immunological Properties of a Tetrasaccharide Portion of the B Side Chain of Rhamnogalacturonan II (RG‐II)
Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA, Fax: (+1) 706-542-4412ChemBioChem (Impact Factor: 3.09). 02/2008; 9(3):381 - 388. DOI: 10.1002/cbic.200700501
A highly convergent strategy was used for the synthesis of a tetrasaccharide [3-aminopropyl beta-L-arabinofuranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->3)]-alpha-L-arabinopyranoside] portion of the B side chain of the plant cell-wall pectic polysaccharide rhamnogalacturonan II (RG-II). The terminal nonreducing beta-L-arabinofuranosyl residue of the target compound was installed by using an arabinofuranosyl donor that was protected with a 3,5-O-(di-tert-butylsilane) group to facilitate nucleophilic attack from the beta-face. The synthetic strategy also employed a chemoselective glycosylation of a trichloroacetimidate donor with a thioglycosyl acceptor; this gave a product that could be used immediately in a subsequent glycosylation. The reducing end of the tetrasaccharide contained an aminopropyl group to facilitate conjugation to keyhole limpet hemocyanin (KLH) and bovine serum albumin (BSA). Mice that were immunized with a KLH-tetrasaccharide conjugate produced antibodies that recognized RG-II isolated from Arabidopsis thaliana cell walls, but did not recognize RG-II obtained from red wine. Our data suggest that the arabinopyranosyl residue exists in the (4)C(1) conformation in the tetrasaccharide and in A. thaliana RG-II, whereas it has the (1)C(4) conformation in wine RG-II. It is proposed that differences in the conformation of side chain B might account for the ability of antibodies to discriminate between RG-II that was isolated from Arabidopsis and wine.
- Advances in Potato Chemistry and Technology, 01/2009: pages 63-81; , ISBN: 9780123743497
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ABSTRACT: Addressing developments in potato chemistry, including identification, analysis and use of chemical components of potatoes in the development of new and innovative food and non-food products; the expert coverage includes a major focus on carbohydrate and non-carbohydrate composition, cell wall chemistry, analysis of glycoalkaloids, phenolics and anthocyanins, thermal processing and quality optimization, new and sophisticated methods of quality determination of potatoes and their products. Potato starch characteristics and its modification, nutritional and feeding value, and non-food uses of potatoes are also explored. Chapters focused on developments in post harvest storage, breeding and germplasm resources and production of potatoes with reference to industrial usage are included.1st edited by Jaspreet Singh, Lovedeep Kaur, 01/2009; Academic Press., ISBN: 978-0-12-374349-7
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ABSTRACT: A major component of the cell wall of mycobacteria is the mycolyl-arabinogalactan (mAG) complex. The arabinose and galactose residues in mAG are found solely in the furanose form, and it has been suggested that the flexibility of these five-membered rings allows for the tight packing of mycolic acids. In order to probe the "flexible scaffold hypothesis", we designed and synthesized glycolipids 3-6 and 8-11 as simple models of the terminal portion of mAG. A set of donors and acceptors were explored for preparing the key beta-(1-->2) linkage in 2-6, and the best selectivity and yield can be obtained by using the electron-rich thioglycoside donor 14 and the O-5 p-methoxybenzyl-protected acceptor 17. Both alpha-linkages in the trisaccharides 7-11 were formed in a one-pot reaction. The conformations of compounds 2-11 were studied using solution-state NMR spectroscopy, but little change was observed in the coupling constants for the ring protons between 2 and 3-6 or between 7 and 8-11. However, the rotamer populations about the C-4-C-5 bond for the beta-linked ring in disaccharide 2 did change upon acylation at O-5.The Journal of Organic Chemistry 08/2010; 75(15):4992-5007. DOI:10.1021/jo100575a · 4.72 Impact Factor
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