Synthesis and immunoreactivity of neoglycoproteins containing the trisaccharide unit of phenolic glycolipid I of Mycobacterium leprae.
The trisaccharide segment, O-(3,6-di-O-methyl-beta-D-glucopyranosyl)-(1----4)-O-(2,3-di-O-methyl- alpha-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-beta-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-beta-D-glucopyranosyl)-(1----4)-O-(2,3-di-O- methyl-alpha-L-rhamnopyranosyl)-(1----2)-(3-O-methyl-alpha-L-rhamnopy ran osyl)- (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.
Chatterjee
D
D
Department of Microbiology, Colorado State University, Fort Collins 80523.
Cho
S N
SN
Stewart
C
C
Douglas
J T
JT
Fujiwara
T
T
Brennan
P J
PJ
D000942:Antigens, Bacterial / Q000276:immunology; D015153:Blotting, Western; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D055598:Chemical Phenomena; D002621:Chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D006017:Glycolipids / Q000138:chemical synthesis*; D006023:Glycoproteins / Q000138:chemical synthesis* / Q000276:immunology; D006031:Glycosylation; D007918:Leprosy / Q000175:diagnosis; D008969:Molecular Sequence Data; D015394:Molecular Structure; D008970:Molecular Weight; D009166:Mycobacterium leprae / Q000276:immunology; D012698:Serologic Tests; D014312:Trisaccharides / Q000138:chemical synthesis* / Q000276:immunology
D000942:Antigens, Bacterial; D006017:Glycolipids; D006023:Glycoproteins; D014312:Trisaccharides; C045169:phenolic glycolipid I, Mycobacterium leprae