A Synthetic Lectin Analog for Biomimetic Disaccharide Recognition

Abstract

was measured with a physical property measurement system. The electrical resistivity shows the MIT at T c = 154 K on cooling ( Fig. 1) and exhibits large thermal hysteresis behavior indicating a first-order character of the MIT. Ca 1.9 Sr 0.1 RuO 4 crystals for scanning tunneling microscopy (STM), LEED, and HREELS measurements were mounted on the sample plates with conducting silver epoxy, and a small metal post was glued on top. The crystal was cleaved by knocking off the post in ultrahigh vacuum with a base pressure of 1.0 × 10 −10 torr, producing a flat shiny [001] surface that yielded a sharp LEED pattern. The STM images of the freshly cleaved surfaces show large micrometer-sized terraces. Both the LEED pattern and atomically resolved STM images indicate that the surface has a well-ordered lattice structure. All surface steps are integral multiples of~6.4 Å , which is the spacing between two nearest-neighbor RuO6 octahedron layers (Fig. 1) 16. S. Nakatsuji et al., Phys. Rev. Lett. 93, 146401 (2003). 17. Detailed spectral data analysis methods were as follows:The Drude weight is the integrated intensity obtained from the difference between the left and right sides of the quasi-elastic peak through a Lorentzian function. Yann Ferrand, Matthew P. Crump, Anthony P. Davis* Carbohydrate recognition is biologically important but intrinsically challenging, for both nature and host-guest chemists. Saccharides are complex, subtly variable, and camouflaged by hydroxyl groups that hinder discrimination between substrate and water. We have developed a rational strategy for the biomimetic recognition of carbohydrates with all-equatorial stereochemistry (b-glucose, analogs, and homologs) and have now applied it to disaccharides such as cellobiose. Our synthetic receptor showed good affinities, not unlike those of some lectins (carbohydrate-binding proteins). Binding was demonstrated by nuclear magnetic resonance, induced circular dichroism, fluorescence spectroscopy, and calorimetry, all methods giving self-consistent results. Selectivity for the target substrates was exceptional; minor changes to disaccharide structure (for instance, cellobiose to lactose) caused almost complete suppression of complex formation. Carbohydrates are challenging substrates for host-guest chemistry (1-4). They possess extended, complex structures that require large receptor frameworks for full encapsulation. The differences between them are often subtle (e.g., the stereochemistry of a single hydroxyl group), so that meaningful selectivity is hard to achieve. Most particularly they are found in water and, with their arrays of hydroxyl groups, they quite strongly resemble water. The first task of a receptor is to discriminate between solvent and substrate, and in the case of carbohydrates this is clearly nontrivial. There is evidence that even nature finds the problem difficult. Though critical for many biological processes (5-7), protein/carbohydrate binding is remarkably weak (8). For example, lectins, the most common class of natural recepto...

Free energy surfaces for the interaction of D-glucose with planar aromatic groups in aqueous solution

“…Lectins, which are the most common class of sugar-binding proteins, bind monosaccharides with binding constants around 10 3 M −1 , 5,6 which corresponds to binding free energies on the order of 10k B T at physiological temperatures. For oligosaccharides the typical binding constants are higher, up to 10 6 -10 7 M −1 .…”

“…7 This is still fairly low and constitutes a challenge to both biochemists and nature itself in the design of carbohydrate-recognizing proteins. 5 The binding sites in sugar-binding proteins often feature the flat side chains of the aromatic amino acids phenylalanine ͑Phe͒, tyrosine ͑Tyr͒, or particularly, tryptophan ͑Trp͒. 8 The extended active sites of cellulases, for example, contain several such residues spaced so as to interact with several sugar rings in cellulose.…”

Progress in the Molecular Design and Synthesis of Organic Fluorescent Probe for Picric Acid Detection

“…鉴于 PA 的 爆炸性大于 TNT, 且对人类和环境的危害性大 [14,15] , 人 们也开始开发聚合物类纯有机分子探针来检测 PA. 其 中, Trogler 课题组 [16,17] 最先从事这方面的工作, 他们从 化合物 1 出发, 利用其与金属锂反应, 分别合成不同的 硅杂环戊二烯类共轭聚合物 2 和 3 (Scheme 1), 它们都 可实现 PA 的检测. 进一步研究发现, 在硅杂环戊二烯共轭聚合物中引 入共轭的 C＝C 双键等结构, 得到的系列荧光共聚物(如 化合物 4～7, 图 1), 同样也可检测 PA, 且猝灭效率更 好.…”

Assembly of Metallohelical Triangle Cryptate for Recognition of Glucosamine

“…It was found that MC-1 exhibited good response of UV-vis and fluorescene toward glucosamine, but no response for glucose. Moreover, 1∶1 stoichiometric host-guest complexation of MC-1 for glucosamine was confirmed by the titration profile and electrospray ionization mass spectrometry (ESI-MS) spectrum, with an association constant (lg K ass ) being calculated as 7 …”