The rates of clinical cure after treatment with fidaxomicin were noninferior to those after treatment with vancomycin. Fidaxomicin was associated with a significantly lower rate of recurrence of C. difficile infection associated with non–North American Pulsed Field type 1 strains. (Funded by Optimer Pharmaceuticals; ClinicalTrials.gov number, NCT00314951.)

No abstract

Useful strategies for the design of molecules to mimic carbohydrates have been developed over the past few years. Mimics of the target may contain new functional groups, a new scaffold, or both (in the schematic representation the natural ligand is shown on the left and the modified version on the right). Many examples of successful carbohydrate mimetics that interfere with sugar-protein and sugar-nucleic acid interactions are known.

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.

Concomitant antibiotic (CA) use compromised initial response to Clostridium difficile infection therapy and durability of that response. Fidaxomicin was significantly more effective than vancomycin in achieving clinical cure in the presence of CAs and preventing recurrence regardless of CA use.

The structure and activity of the pseudodisaccharide core found in aminoglycoside antibiotics was probed with a series of synthetic analogues in which the position of amino groups was varied around the glucopyranose ring. The naturally occurring structure neamine was the best in the series according to assays for in vitro RNA binding and antibiotic activity. With this result in hand, neamine was used as a common core structure for the synthesis of new antibiotics, which were evaluated for binding to models of the Escherichia coli 16S A-site ribosomal RNA, in vitro protein synthesis inhibition, and antibiotic activity. Analysis of RNA binding revealed some correlation between the relative affinity and specificity of RNA binding and antibacterial efficacy. However, the correlation was not linear. This result led us to develop the in vitro translation assay in an effort to better understand aminoglycoside−RNA interactions. A linear correlation between in vitro translation inhibition and antibiotic activity was observed. In addition, IC50s in the protein synthesis assay were typically lower than the K ds obtained for RNA binding, suggesting that binding of these compounds to intact ribosomes is tighter in these cases than binding to the model RNA oligonucleotides. This reflects possible differences in RNA conformation between intact ribosomes and the free RNA of the model system, or possible high-affinity ribosomal binding sites in addition to the A-site RNA.

Just a few decades ago, the saccharides bound to glycoproteins were considered little more than an irritation. They increased the difficulty of purifying and characterizing proteins, making proteins run as several bands on gels and smearing them on columns. They were considered a nuisance and were typically cleaved away to reveal the 'important part', the protein moiety, for structural (e.g. via X-ray crystallography or nuclear magnetic resonance) and functional studies. We now realize that that the saccharide is often as important as the protein itself, and that glycosylation can have many effects on the function, structure, physical properties and targeting of a protein. There are a myriad of reviews and books on this subject, reflecting the nearly overwhelming number of articles in print discussing saccharide structures, glycoprotein processing enzymes and the biological implication of glycosylation. This review discusses, in turn, the extent and biological relevance of glycosylation; the structures observed; how glycosylated proteins are formed in vivo; the clinical relevance of glycosylation, in terms of the correlations between disease states and unusual glycosylation patterns; and, finally, the molecules, both natural and synthetic, that can be used to study the role of carbohydrates in glycoprotein structure and function or to disrupt various carbohydrate recognition processes and enzymatic reactions in the glycoprotein synthetic pathway.

In order to study the effects carbohydrates have on glycoprotein structure and function, it is imperative to be able to synthesize the appropriate natural and non-natural glycoprotein variants in a single form. Because the available in ViVo techniques provide only heterogeneous mixtures of different glycoforms, enzymatic in Vitro methodologies have been pursued. Using the N-glycoprotein RNase B as a model system, the oligosaccharide was removed leaving only the N-acetylglucosamine as a "tag" to the site of glycosylation. Glycosyltransferases were then used to build a unique carbohydrate moiety. A new RNase glycoform containing the branched oligosaccharide, sialyl Lewis X or the Hg derivative, was synthesized enzymatically to demonstrate the feasibility of the method. In addition, the monoglycosylated protein was digested into several smaller pieces by subtilisin BPN′. These fragments were religated by subtilisin 8397 to the full length RNase by addition of glycerol; this method points to a new chemical-enzymatic process for the synthesis of glycoproteins using synthetic peptides and glycopeptides as substrates for enzymatic ligation followed by further enzymatic glycosylations.