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A carbohydrate-antioxidant hybrid polymer reduces oxidative damage in spermatozoa and enhances fertility.
Gamete-gamete interactions are critically modulated by carbohydrate-protein interactions that rely on the carbohydrate-selective recognition of polyvalent carbohydrate structures. A galactose-binding protein has been identified in mammalian spermatozoa that has similarity to the well-characterized hepatic as…
Light-driven post-translational installation of reactive protein side chains.
Post-translational modifications (PTMs) greatly expand the structures and functions of proteins in nature1,2. Although synthetic protein functionalization strategies allow mimicry of PTMs3,4, as well as formation of unnatural protein variants with diverse potential functions, including drug carrying5, tracking, i…
Detailed insights from microarray and crystallographic studies into carbohydrate recognition by microneme protein 1 (MIC1) of Toxoplasma gondii.
The intracellular protozoan Toxoplasma gondii is among the most widespread parasites. The broad host cell range of the parasite can be explained by carbohydrate microarray screening analyses that have demonstrated the ability of the T. gondii adhesive protein, TgMIC1, to bind to a wide spectrum of sial…
Synthetic post-translational modification of histones.
Chromatin is the physiological template of genetic information in all eukaryotic cells, a highly organised complex of DNA and histone proteins central in regulating gene expression and genome organisation. A multitude of histone post-translational modifications (PTMs) have been discovered, providing a glan…
Analysis of the Tunicamycin Biosynthetic Gene Cluster of Streptomyces chartreusis Reveals New Insights into Tunicamycin Production and Immunity.
The tunicamycin biosynthetic gene cluster of Streptomyces chartreusis consists of 14 genes (tunA to tunN) with a high degree of apparent translational coupling. Transcriptional analysis revealed that all of these genes are likely to be transcribed as a single operon from two promoters, tunp1 and tunp2. In-fr…
A front-face 'SNi synthase' engineered from a retaining 'double-SN2' hydrolase.
SNi-like mechanisms, which involve front-face leaving group departure and nucleophile approach, have been observed experimentally and computationally in chemical and enzymatic substitution at α-glycosyl electrophiles. Since SNi-like, SN1 and SN2 substitution pathways can be energetically comparable, engine…
Single-molecule interrogation of a bacterial sugar transporter allows the discovery of an extracellular inhibitor.
Capsular polysaccharides form the outermost protective layer around many Gram-negative bacteria. Antibiotics aimed directly at weakening this layer are not yet available. In pathogenic Escherichia coli E69, a protein, Wza, forms a pore in the outer membrane that transports K30 capsular polysaccharide from…
Sugar synthesis in a protocellular model leads to a cell signalling response in bacteria.
The design of systems with life-like properties from simple chemical components may offer insights into biological processes, with the ultimate goal of creating an artificial chemical cell that would be considered to be alive. Most efforts to create artificial cells have concentrated on systems based on compl…
Chemical modification of biocatalysts.
Although several powerful methods exist for the redesign of enzyme structure and function these are typically limited to the 20 most abundant proteinogenic amino acids. The use of chemical modification overcomes this limitation to allow virtually unlimited alteration of amino acid sidechain structures. If heterog…
Structural dissection and high-throughput screening of mannosylglycerate synthase.
The enzymatic transfer of activated mannose yields mannosides in glycoconjugates and oligo- and polysaccharides. Yet, despite its biological necessity, the mechanism by which glycosyltransferases recognize mannose and catalyze its transfer to acceptor molecules is poorly understood. Here, we report broad…
Controlled site-selective protein glycosylation for precise glycan structure-catalytic activity relationships.
Glycoproteins occur naturally as complex mixtures of differently glycosylated forms which are difficult to separate. To explore their individual properties, there is a need for homogeneous sources of carbohydrate-protein conjugates and this has recently prompted us to develop a novel method for the site-sel…
Site-selective glycosylation of subtilisin Bacillus lentus causes dramatic increases in esterase activity.
Using site directed mutagenesis combined with chemical modification, we have developed a general and versatile method for the glycosylation of proteins which is virtually unlimited in the scope of proteins and glycans that may be conjugated and in which the site of glycosylation and the nature of the introduc…
An autonomous molecular assembler for programmable chemical synthesis.
Molecular machines that assemble polymers in a programmed sequence are fundamental to life. They are also an achievable goal of nanotechnology. Here, we report synthetic molecular machinery made from DNA that controls and records the formation of covalent bonds. We show that an autonomous cascad…
Filled and glycosylated carbon nanotubes for in vivo radioemitter localization and imaging.
Functionalization of nanomaterials for precise biomedical function is an emerging trend in nanotechnology. Carbon nanotubes are attractive as multifunctional carrier systems because payload can be encapsulated in internal space whilst outer surfaces can be chemically modified. Yet, despite poten…
Chemical site-selective prenylation of proteins.
A direct thionation procedure allows conversion of allylic alcohols into the corresponding thiols, the products of which are immediately compatible with one-pot site-selective selenenyl sulfide mediated protein conjugation.
Chemical polyglycosylation and nanolitre detection enables single-molecule recapitulation of bacterial sugar export.
The outermost protective layer of both Gram-positive and Gram-negative bacteria is composed of bacterial capsular polysaccharides. Insights into the interactions between the capsular polysaccharide and its transporter and the mechanism of sugar export would not only increase our understanding of this…