Structural knowledge of naturally occurring, biologically important molecules is at the very foundation of modern biochemistry and biology. When an unprecedented and unanticipated type of molecular structure is suddenly discovered, one therefore imagines that either ‘the microscope has got bigger’, or that someone was lucky and stumbled onto something, or paid exceptional attention to detail. In the case of Vinogradov and Bock — who, in Angewandte Chemie International Edition (38, 671-674; 1999) report the discovery of a new type of sugar-sugar linkage in bacterial polysaccharides — all three events occurred simultaneously.
The procedures for determining the primary sequences of DNA and proteins or peptides are well known from textbooks, and commercial instruments are available that perform the required chemistry and analysis. This is not so in the case of oligosaccharides and polysaccharides. Polynucleic acids (such as DNA and RNA) and proteins are assembled from a limited number of monomers, whereas hundreds are available for building polysaccharides. Further, carbohydrate polymers do not have to be linear but can be branched, and the joining of sugar units together in glycosidic linkages involves the creation of a new stereochemical centre at the point of attachment.
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