GLYCAN STRUCTURE OF A HEPTOSE-CONTAINING S-LAYER GLYCOPROTEIN OF BACILLUS-THERMOAEROPHILUS

The characterization of the S-layer glycoprotein of Bacillus thermoaer ophilus revealed unexpected novelties, The isolation and purification procedure had to be changed due to complete solubility in aqueous buff ers of the constituting S-layer protomers, Upon degradation of the S-l ayer glycoprotein by pronase and purification of the products by gel f iltration, ion-exchange chromatography, chromatofocusing and HPLC, one representative glycopeptide fraction was selected for further charact erization. From the combined evidence of composition analysis, chemica l degradation, NMR spectroscopy experiments and comparison with synthe sized model substance, we propose the following repeating unit structu re of the glycan chain: --> 4)-alpha-L-Rhap-(1 --> 3)-beta-D-glycero-D -manno-Hepp-(1 --> This is the first description of heptose residues o ccurring as a constituent of S-layer glycoproteins of gram-positive eu bacteria.