The presence of novel glucuronic acid-containing, type-specific glycolipid antigens within Mycobacterium spp. Revision of earlier structures

Previously, we had described the structures of the haptenic oligosaccharides of the surface glycopeptidolipid antigens from serotypes 9 and 25 of the Mycobacterium avium complex and had synthesized these units as putative antigenic probes. The lack of chemical concordance between the synthetic products and the haptens has prompted a re-examination of these structures utilizing the instrumental techniques not previously available of fast atom bombardment-mass spectrometry, Fourier transform infra-red, and high resolution NMR spectroscopy. With the additional information thus available, more extensive chemical fragmentations by base degradation, followed by alkylation, have furnished supportive evidence to allow formulation of revised and novel structures, all of which contain glucuronic acid: serotype 9, 2,3-di-O-Me-L-Fucp(alpha 1----4)-D-GlcAp(beta 1----4)-2,3-di-O-Me-L-Fucp(alpha 1----3)-L-Rhap(alpha 1----2)-6dTal; and serotype 25, 4-acetamido-4,6-dideoxy-2-O-Me-hexosyl(alpha 1----4)-D- GlcAp(beta 1----4)2-O-Me-L-Fucp(alpha 1----3)-L-Rhap(alpha 1----2)6dTal. Glucuronic acid, acetamido sugars, and other novel sugars appear to be widespread in the glycopeptidolipid antigens of Mycobacterium spp. The revised structures will allow renewed synthesis of artificial antigen probes and rational approaches to preparing monoclonal antibodies, both necessary for the new diagnostics required to trace the sources of widespread infections due to M. avium and Mycobacterium intracellulare.