Synthesis and immunoreactivity of neoglycoproteins containing the trisaccharide unit of phenolic glycolipid I of Mycobacterium leprae

Delphi Chatterjee, Sang Nae Cho, Carol Stewart, James T. Douglas, Tsuyoshi Fujiwara, Patrick J. Brennan

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Abstract

The trisaccharide segment, O-(3,6-di-O-methyl-β-d-glucopyranosyl)-(1→4)-O-(2,3-di-O-methyl-α-l-rhamnopyranosyl)-(1→2)- 3-O-methyl-l-rhamnopyranose, of the Mycobacterium leprae-specific phenolic glycolipid I has been synthesized as its 8-(methoxycarbonyl)octyl glycoside and coupled to a carrier protein, to produce a leprosy-specific neoglycoprotein, the so-called natural trisaccharide-octyl-bovine serum albumin (NT-O-BSA). Special features of the synthetic strategy were the use of silver trifluoromethanesulfonate (triflate) to promote glycosylation, resulting in the rhamnobiose in high yield and absolute stereospecificity. The terminal 3,6-di-O-methyl-d-glucopyranosyl group was introduced after O-deallylation of the rhamnobiose. Removal of protecting groups yielded the trisaccharide hapten suitable for coupling to carrier protein. Poly(acrylamide)-gel electrophoresis of the neoglycoprotein demonstrated its purity, and subsequent immunoblotting with a monoclonal antibody directed to the terminal 3,6-di-O-methyl-β-d-glucopyranosyl epitope of the native glycolipid demonstrated its antigenicity. Comparative serological testing in enzyme-linked immunosorbent assays of NT-O-BSA, the corresponding disaccharide-containing products, and another trisaccharide-containing neoglycoprotein, O-(3,6-di-O-methyl-β-d-glucopyranosyl)-(1→4)-O-(2,3-di-O-methyl-α-l-rhamnopyranosyl)-(1→2)-(3-O- methyl-α-l-rhamnopyranosyl)-(1→4′)-oxy-(3-phenylpropanoyl)-BSA (NT-P-BSA) [Fujiwara et al., Agric. Biol. Chem., 51 (1987) 2539-2547] against sera from leprosy patients and control populations showed concordance; the presence of the innermost sugar did not contribute significantly to sensitivity or specificity. The di- and tri-saccharide-containing neoantigens, on account of ready availability and solubility, provide greater flexibility than the native glycolipid for the serodiagnosis of leprosy.

Original languageEnglish
Pages (from-to)241-260
Number of pages20
JournalCarbohydrate Research
Volume183
Issue number2
DOIs
Publication statusPublished - 1988 Dec 1

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All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

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