8A Chemical Reviews, 2000, Vol. 100, No. 12
In Color on the Front Cover (Top left) Nature, especially plants, abounds with carbohydrates. This vast chemical resource has largely been untapped. A wide spectrum of general-purpose chiral intermediates can now be obtained from lactose, maltose, arabinose, starch, and cellulose. See “Toward a Carbohydrate-Based Chemistry: Progress in the Development of General-Purpose Chiral Synthons from Carbohydrates” by Rawle I. Hollingsworth and Guijun Wang, p 4267. (Top right) Emil Fischer founded both preparative carbohydrate and peptide chemistry. During the past decades the important biological functions of glycoproteins, combined from saccharide and peptide portions, have been recognized. Although glycopeptide synthesis is a much younger field than peptide synthesis, chemical methodology has now achieved a level that makes complex partial structures and model compounds of glycoproteins available in pure form. See “Synthesis of Glycopeptides Containing Carbohydrate and Peptide Recognition Motifs” by Holger Herzner, Tanja Reipen, Michael Schultz, and Horst Kunz, p 4495. (Bottom left) Siallylactose in the binding site of Maackia amurensis leukoagglutinin. Close-up of the crystal structure displayed in Figure 5. See “Structure, Conformation, and Dynamics of Bioactive Oligosaccharides: Theoretical Approaches and Experimental Validations” by Anne Imberty and Serge Pe´rez, p 4567. (Bottom right) The high-affinity interaction between P-selection and its glycoprotein ligand PSGL-1 relies on the presence of a core 2-O-linked glycan-containing sialyl Lewis x (sLex) and at least one site of tyrosine sulfation. See “Synthesis of Complex Carbohydrates and Glycoconjugates: Enzyme-Based and Programmable One-Pot Strategies” by Kathryn M. Koeller and Chi-Huey Wong, p 4465. In Color on the Inside Front Cover (Bottom left) Replacing the amide group of natural N-acetal-galactosyl asparagine-containing peptides with an ethylene group leads to chemically and enzymatically more stable systems. Totally artificial glycopeptides are prepared by newly designed sugar amino acids whose carbon atom is shared by the glycinyl moiety. See “Methods for Anomeric Carbon-Linked and Fused Sugar Amino Acid Synthesis: The Gateway to Artificial Glycopeptides” by Alessandro Dondoni and Alberto Marra, p 4395. (Bottom right) Carbohydrates are versatile ligands for platinum-group metals. Thus, P-functionalized carbohydrates are excellent co-ligands for enantioselective catalysts and platinum(IV), a high oxidation state transition metal, can bind nonfunctionalized carbohydrates, although they are weak donors. See “Carbohydrate Complexes of Platinum-Group Metals” by Dirk Steinborn and Henrik Junicke, p 4283. In Color on the Inside Back Cover (Middle right) Structural relationship between NB-DNJ and ceramide: (a) crystal structure of ceramide showing the acceptor hydroxyl from glucose on C1′. (b) NMR solution structure of NB-DNJ. Modification of those groups which define changes in activity are shown. (c) Possible overlay of NB-DNJ and ceramide showing structural mimicry. (Reprinted with permission from ref 79. Copyright 2000 Elsevier Science Ltd.) See “The Inhibition of Glycosphingolipid Biosynthesis: Application to Lysosomal Storage Disorders” by Terry D. Butters, Raymond A. Dwek, and Frances M. Platt, p 4683. (Bottom right) Representation of the interactions (Watson−Crick type) between a natural dinucleotide “A−A” (with phosphate bridge) and a modified nucleotide “T/T” (with “O−CO−NH−NdCH” bridge) in water. Dashed lines (in purple) indicate hydrogen-bonding contact distances which are responsible for the stabilization of the aggregate: (red) oxygen atoms, (blue) nitrogen atoms, (grey) carbon atoms, (green) phosphorus atoms. AA + T/T f AA− T/T; ∆Hf (AA−T/T) ) −5.770 kcal/mol. AA + TT f AA−TT; ∆Hf (AA−TT) ) +17.052 kcal/mol. See “Biocatalytic Selective Modifications of Conventional Nucleosides, Carbocyclic Nucleosides, and C-Nucleosides” by Miguel Ferrero and Vicente Gotor, p 4319. In Color on the Back Cover (Top) Heteroaromatic glycosides derived from 3-methoxy-2-hydroxypyridine (MOP) are excellent glycosyl donors that transfer the sugar moiety to a variety of acceptors (nucleophiles) without the need for hydroxyl protection. Reactions are highly stereocontrolled affording glycosides, oligosaccharides, 1-phosphates, and 1-carboxylates reminiscent of enzymatic glycosyl transfers. See “Stereocontrolled Glycosyl Transfer Reactions with Unprotected Glycosyl Donors” by Stephen Hanessian and Boliang Lou, p 4443.
