There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Inference of macromolecular assemblies from crystalline state.

Chitin and chitosan: Properties and applications

Antimicrobial host defense peptides are produced by all complex organisms as well as some microbes and have diverse and complex antimicrobial activities. Collectively these peptides demonstrate a broad range of antiviral and antibacterial activities and modes of action, and it is important to distinguish between direct microbicidal and indirect activities against such pathogens. The structural requirements of peptides for antiviral and antibacterial activities are evaluated in light of the diverse set of primary and secondary structures described for host defense peptides. Peptides with antifungal and antiparasitic activities are discussed in less detail, although the broad-spectrum activities of such peptides indicate that they are important host defense molecules. Knowledge regarding the relationship between peptide structure and function as well as their mechanism of action is being applied in the design of antimicrobial peptide variants as potential novel therapeutic agents.

Peptide Antimicrobial Agents

Structure, Conformation, and Dynamics of Bioactive Oligosaccharides: Theoretical Approaches and Experimental Validations

Flexibility in a tetrasaccharide fragment from the high mannose type of N-linked oligosaccharides.

Burkholderia ambifaria is a bacterium member of the Burkholderia cepacia complex (BCC), a closely related group of Gram-negative bacteria responsible for “cepacia syndrome” in immunocompromised patients. B. ambifaria produces BambL, a fucose-binding lectin that displays fine specificity to human fucosylated epitopes. Here, we report the first example of a synthetic ligand able to selectively bind, in the micromolar range, the pathogen-lectin BambL. The synthetic routes for the preparation of the α conformationally constrained fucoside are described, focusing on a totally diastereoselective inverse electron demand [4 + 2] Diels–Alder reaction. Isothermal titration calorimetry (ITC) demonstrated that this compound binds to the pathogen-associated lectin BambL with an affinity comparable to that of natural fucose-containing oligosaccharides. No binding was observed by LecB, a fucose-binding lectin from Pseudomonas aeruginosa, and the differences in affinity between the two lectins could be rationalized by modeling. Furthermore, SPR analyses showed that this fucomimetic does not bind to the human fucose-binding lectin DC-SIGN, thus supporting the selective binding profile towards B. ambifaria lectin.

/pdf/synthesis-of-a-selective-inhibitor-of-a-fucose-binding-1aspenm7wr.pdf

Synthesis of a selective inhibitor of a fucose binding bacterial lectin from Burkholderia ambifaria

The large diversity and complexity of glycan structures together with their crucial role in many biological or pathological processes require the development of new high-throughput techniques for analyses. Lectins are classically used for characterising, imaging or targeting glycoconjugates and, when printed on microarrays, they are very useful tools for profiling glycomes. Development of recombinant lectins gives access to reliable and reproducible material, while engineering of new binding sites on existing scaffolds allows tuning of specificity. From the accumulated knowledge on protein–carbohydrate interactions, it is now possible to use nucleotide and peptide (bio)synthesis for producing new carbohydrate-binding molecules. Such a biomimetic approach can also be addressed by boron chemistry and supra-molecular chemistry for the design of fully artificial glycosensors.

Anne Imberty

Papers

Structure, Conformation, and Dynamics of Bioactive Oligosaccharides: Theoretical Approaches and Experimental Validations

Flexibility in a tetrasaccharide fragment from the high mannose type of N-linked oligosaccharides.

Synthesis of a selective inhibitor of a fucose binding bacterial lectin from Burkholderia ambifaria

Binding Sugars: From Natural Lectins to Synthetic Receptors and Engineered Neolectins

Multivalent Glycomimetics with Affinity and Selectivity toward Fucose-Binding Receptors from Emerging Pathogens