Glycoproteins, glycolipids, and glycophospholipids (glycoconjugates) are components of membranes. The oligosaccharide residue is responsible for intercellular recognition and interaction; it acts as a receptor for proteins, hormones, and viruses and governs immune reactions. These significant activities have stimulated interest in oligosaccharides and glycoconjugates. With their help it should be possible to clarify the molecular basis of these phenomena and to derive new principles of physiological activity. Major advances in the synthesis of oligosaccharides have been made by the use of the Koenigs-Knorr method, in which glycosyl halides in the presence of heavy-metal salts are employed to transfer the glycosyl group to nucleophiles. The disadvantages of this procedure have led to an intensive search for new methods. Such methods will be discussed in this article. Emphasis is placed on glycoside and saccharide formation by 1-O-alkylation, on the trichloroacetimidate method, and on activation through the formation of glycosylsulfonium salts and glycosyl fluorides.

New Methods for the Synthesis of Glycosides and Oligosaccharides—Are There Alternatives to the Koenigs‐Knorr Method? [New Synthetic Methods (56)]

A wide variety of complex oligosaccharides has now been made accessible as a result of methodological improvements in the sphere of chemical synthesis, which can be used for the study of conformations and interactions with protein-receptor molecules. Such work is of particular importance because the oligosaccharide chains of glycoproteins and glycolipids anchored to the plasma membrane are important in cell-cell interactions and are receptors for enzymes, hormones, proteins, and viruses; furthermore, they determine the antigen properties of cells. The methods of synthesis available for the production of selective linkages in oligosaccharides are dealt with, particular attention being paid to conversion of saccharides into oligosaccharides, which are important from the biological point of view.

Advances in Selective Chemical Syntheses of Complex Oligosaccharides

The discovery of previously unknown functions associated with carbohydrates and the study of their structure-function relations are of current interest in carbohydrate chemistry and biology. Progress in this area is, however, hampered by the lack of convenient and effective tools for the synthesis and analysis of oligosaccharides and glycoconjugates. Development of automated synthesis of such materials is necessary to facilitate research in this field. This review describes recent advances in carbohydrate synthesis, with particular focus on developments that have potential application to the automated synthesis of oligosaccharides, glycopeptides, and glycoproteins.

https://science.sciencemag.org/content/sci/291/5512/2344.full.pdf

Toward automated synthesis of oligosaccharides and glycoproteins.

Glycoproteine, Glycolipide und Glycophospholipide (=Glycokonjugate) sind Bestandteile von Membranen. Dabei ist der oligosaccharidische Teil fur Zell-Zell-Erkennung und -Wechselwirkung zustandig; er fungiert als Rezeptor fur Proteine, Hormone und Viren und determiniert Immunreaktionen. Diese Bedeutung hat das Interesse an Oligosacchariden und Glycokonjugaten stimuliert. Mit ihnen sollte es gelingen, die molekulare Basis dieser Phanomene aufzuklaren und neue physiologische Wirkprinzipien abzuleiten. Grose Fortschritte der Oligosaccharidsynthese sind mit der Koenigs-Knorr-Methode erzielt worden, bei der Halogenosen in Gegenwart von Schwermetallsalzen zur Glycosylubertragung auf Nucleophile dienen. Die Nachteile dieses Verfahrens haben zu einer intensiven Suche nach neuen Methoden gefuhrt. In diesem Beitrag werden solche Methoden diskutiert. Dabei ist insbesondere auf die Glycosid- und Saccharidbildung durch 1-O-Alkylierung, auf die Trichloracetimidat-Methode und auf die Aktivierung uber Glycosylsulfoniumsalze und Glycosylfluoride hinzuweisen.

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Neue Methoden zur Glycosid- und Oligosaccharidsynthese – gibt es Alternativen zur Koenigs-Knorr-Methode?

Many inherited polymorphisms in plasma proteins and in enzyme activities of red blood cells are now available as genetic markers to differentiate bloods within a species (see Giblett, 1969, and Harris, 1975). However, the term “blood groups” is still usually retained to describe antigenic differences detected on the red cell surface by means of specific antibodies. Macromolecules occurring in secretions of the same or different species which carry serological specificities related to the red cell antigens are called blood group substances; these substances are designated by the letter or symbol assigned to the corresponding antigen on the red cell surface. In man fifteen well-defined independent blood group systems are recognized, each comprising antigens believed to be the products of alleles at one gene locus or of closely linked gene loci. In addition, there are some very frequent (“public”) and infrequent (“private”) antigens which may belong to established systems or may be parts of new systems (see Race and Sanger, 1975). For only three blood group systems, namely ABO, Lewis, and P, is the chemical nature of the antigens unequivocally established, and this review will be primarily concerned with these systems.

K. James

Papers

Halide ion catalyzed glycosidation reactions. Syntheses of .alpha.-linked disaccharides