Non-Covalent Bonding

非共价键合
  • 文章类型: Journal Article
    多面体分子因其引人注目的结构和独特的化学而吸引人。这样的全氟化,通常会产生很大的应变,是一个重大挑战。它极大地改变了电子分布,结构和属性。值得注意的是,小型高对称性全氟多面体的特征是位于中央,星形低能未占据的分子轨道,可以在多面体框架内承载一个额外的电子,从而产生自由基阴离子,不失去对称性。这种预测的电子托管能力肯定是为全氟卡布确定的,第一个被分离纯的全氟化柏拉图式多面体。承载原子,这种“笼子”结构中的分子或离子是,然而,除了直率,当不是虚幻的时候,提供不容易获得超分子结构。虽然金刚烷和古巴在材料科学中促进了许多应用,医学和生物学,其全氟对应物的具体用途仍有待确定。高氟化碳同素异形体的某些方面,如富勒烯或石墨,简要提及上下文。
    Polyhedral molecules are appealing for their eye-catching architecture and distinctive chemistry. Perfluorination of such, often greatly strained, compounds is a momentous challenge. It drastically changes the electron distribution, structure and properties. Notably, small high-symmetry perfluoropolyhedranes feature a centrally located, star-shaped low-energy unoccupied molecular orbital that can host an extra electron within the polyhedral frame, thus producing a radical anion, without loss of symmetry. This predicted electron-hosting capacity was definitively established for perfluorocubane, the first perfluorinated Platonic polyhedrane to be isolated pure. Hosting atoms, molecules, or ions in such \"cage\" structures is, however, all but forthright, if not illusionary, offering no easy access to supramolecular constructs. While adamantane and cubane have fostered numerous applications in materials science, medicine, and biology, specific uses for their perfluorinated counterparts remain to be established. Some aspects of highly fluorinated carbon allotropes, such as fullerenes and graphite, are briefly mentioned for context.
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  • 文章类型: Journal Article
    核酸适体是特异性识别靶标的ssDNA或ssRNA片段。然而,由4种天然核苷(A,G,C,T/U)的结合亲和力通常比同源抗体差。高亲和力修饰策略的发展在适体应用中引起了广泛关注。具有稳定三维形状的化学修饰的适体可以通过增强的非共价键与靶蛋白紧密相互作用,可能导致数百个亲和力增强。这篇综述概述了适体中使用的高亲和力修饰策略,包括核碱基修饰,氟修饰(2'-氟核酸,2'-氟阿拉伯核酸,2\',2'-二氟核酸),结构改变修饰(锁核酸,解锁核酸),磷酸盐修饰(硫代磷酸酯,二硫代磷酸酯),和扩展字母。该综述强调了这些高亲和力修饰如何作为与靶蛋白的相互作用而起作用。从而完善适体的药效学特性。
    Nucleic acid aptamers are ssDNA or ssRNA fragments that specifically recognize targets. However, the pharmacodynamic properties of natural aptamers consisting of 4 naturally occurring nucleosides (A, G, C, T/U) are generally restricted for inferior binding affinity than the cognate antibodies. The development of high-affinity modification strategies has attracted extensive attention in aptamer applications. Chemically modified aptamers with stable three-dimensional shapes can tightly interact with the target proteins via enhanced non-covalent bonding, possibly resulting in hundreds of affinity enhancements. This review overviewed high-affinity modification strategies used in aptamers, including nucleobase modifications, fluorine modifications (2\'-fluoro nucleic acid, 2\'-fluoro arabino nucleic acid, 2\',2\'-difluoro nucleic acid), structural alteration modifications (locked nucleic acid, unlocked nucleic acid), phosphate modifications (phosphorothioates, phosphorodithioates), and extended alphabets. The review emphasized how these high-affinity modifications function in effect as the interactions with target proteins, thereby refining the pharmacodynamic properties of aptamers.
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  • 文章类型: Journal Article
    最近,microRNAs(miRNA)作为新的诊断和预后生物标志物获得了关注,它们有可能早期出现多种病理。由于miRNA是一个短,非编码RNA序列,它们检测的灵敏度和选择性仍然是科学研究的基石。因此,基于纳米材料的方法已经出现,希望开发快速和容易的方法。基于纳米技术的检测方法的核心是纳米探针和其他功能化纳米材料。由于miRNA的传感和检测通常植根于用寡核苷酸的互补序列捕获靶miRNA,序列需要以特定的缀合策略连接到纳米材料上。由于每种纳米材料都有其独特的性质,每种共轭方法都有其缺点和优点,这篇综述简要概述了基于纳米材料的miRNA传感中的缀合方法。首先简要概述可用作基材的纳米材料的特定性质和特征,然后重点集中在共价和非共价键化学上,导致纳米材料的功能化,这是最常用的miRNA传感方法。
    Recently, microRNAs (miRNA) captured the interest as novel diagnostic and prognostic biomarkers, with their potential for early indication of numerous pathologies. Since miRNA is a short, non-coding RNA sequence, the sensitivity and selectivity of their detection remain a cornerstone of scientific research. As such, methods based on nanomaterials have emerged in hopes of developing fast and facile approaches. At the core of the detection method based on nanotechnology lie nanoprobes and other functionalized nanomaterials. Since miRNA sensing and detection are generally rooted in the capture of target miRNA with the complementary sequence of oligonucleotides, the sequence needs to be attached to the nanomaterial with a specific conjugation strategy. As each nanomaterial has its unique properties, and each conjugation approach presents its drawbacks and advantages, this review offers a condensed overview of the conjugation approaches in nanomaterial-based miRNA sensing. Starting with a brief recapitulation of specific properties and characteristics of nanomaterials that can be used as a substrate, the focus is then centered on covalent and non-covalent bonding chemistry, leading to the functionalization of the nanomaterials, which are the most commonly used in miRNA sensing methods.
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  • 文章类型: Journal Article
    在这项研究中,我们建议使用术语Wolfium键(WfB)来指代第6族任何元素与电子供体原子(中性分子或阴离子)之间的净吸引力(非共价相互作用),并将其与配位键区分开(金属-配体相互作用)。我们通过检查来自蛋白质数据库(PDB)的包含钼蝶呤和钨蝶呤辅因子的蛋白质的X射线晶体结构,提供了这种相互作用存在的证据。还通过从头算计算(RI-MP2/def2-TZVP理论水平)分析了相互作用的合理生物学作用及其物理性质(涉及反键合Wf-配体轨道),分子中的原子(AIM)自然键轨道(NBO)和非共价相互作用图(NCIplot)分析。
    In this study we propose to coin the term Wolfium bond (WfB) to refer to a net attractive force (noncovalent interaction) between any element of group 6 and electron donor atoms (neutral molecules or anions) and to differentiate it from a coordination bond (metal-ligand interaction). We provide evidence of the existence of this interaction by inspecting the X-ray crystal structure of proteins containing Molybdopterin and Tungstopterin cofactors from the Protein Data Bank (PDB). The plausible biological role of the interaction as well as its physical nature (antibonding Wf-Ligand orbital involved) are also analyzed by means of ab initio calculations (RI-MP2/def2-TZVP level of theory), Atoms in Molecules (AIM), Natural Bond Orbital (NBO) and Noncovalent Interactions plot (NCIplot) analyses.
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  • 文章类型: Journal Article
    提出术语单核(Sp)键是指第12族的任何元素与富电子原子(路易斯碱或阴离子)之间的净吸引相互作用。这些非共价相互作用与配位键(涉及反键Sp-配体轨道)明显不同。通过理论的RI-MP2/aug-cc-pVTZ水平的计算,提供了这种相互作用存在的证据,分子中的原子,和自然键轨道分析,并通过检查剑桥结构数据库中的固态结构。
    The term spodium (Sp) bond is proposed to refer to a net attractive interaction between any element of Group 12 and electron-rich atoms (Lewis bases or anions). These noncovalent interactions are markedly different from coordination bonds (antibonding Sp-ligand orbital involved). Evidence is provided for the existence of this interaction by calculations at the RI-MP2/aug-cc-pVTZ level of theory, atoms-in-molecules, and natural bond orbital analyses and by examining solid-state structures in the Cambridge Structure Database.
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  • 文章类型: Comparative Study
    Both defatted peanut flour (DPF) and peanut protein isolate (PPI) are widely used to prepare peanut protein hydrolysates. To compare their enzymatic hydrolysis efficiencies, DPF and PPI were hydrolysed by Alcalase, Neutrase, Papain, Protamex and Flavorzyme. Alcalase and Flavorzyme were found to be the most efficient proteases to hydrolyse both DPF and PPI. The efficiency was comparable to each other when using Alcalase, while PPI was hydrolysed less efficiently than DPF when using Flavorzyme. Analysis of changes in the protein solubility, subunit and conformation, and amino acid composition of DPF, PPI and their Flavorzyme hydrolysis residues indicated that the PPI preparation process had minimal effect on it, but peptide aggregation via non-covalent bonding (including hydrophobic interactions and hydrogen bonds) during hydrolysis and/or thermal treatment after hydrolysis were likely responsible for the reduced hydrolysis efficiency of PPI by Flavorzyme.
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