Assessing sialic acid content in food by hydrophilic chromatography-high performance liquid chromatography

We have established a novel hydrophilic chromatography (HILIC)-high performance liquid chromatography (HPLC) method to assess sialic acid content in food products. Single-factor and response surface methodologies (RSM) were used to systematically optimize the hydrolysis conditions of the food samples to extract the maximum amount of sialic acid. Chromatographic conditions were also adjusted. In foods containing sialic acid, we observed a strong linear relationship between sialic acid and peak area, ranging from 5 to 100 μg/mL (R² = 0.9998). The lowest detectable sialic acid concentration (RSN = 3) was 0.2 μg mL⁻¹, and the method detection limit was 0.02mg kg⁻¹. Sample recovery ranged from 95.85% to 99.78%, with an RSD of 1.46% (n = 6). Thus, the described method can be applied to the study of sialic acid content in foods.     

DNA编码化合物库技术新进展及其在生物医药领域的应用与展望

随着医药领域对靶向调节特定生命活动过程的新分子化合物的需求日益增加,高效、低成本地发现亲和配体分子的新型小分子药物筛选技术——DNA编码的化合物库(DNA encoded compound library,DEL)筛选技术应运而生。DEL作为组合化合物库,可以是简单小分子化合物的集合,也可以是具有高级空间结构的复杂小分子库,每个化合物都以共价方式与特异的DNA序列偶联,因而可将库中所有化合物与靶标蛋白进行合并筛选,随后使用高通量测序对DNA编码序列进行测序来鉴定结合的配体分子。近年来,应用DEL技术筛选开发候选药物的例子已越来越多地被报道,本文回顾和总结了DEL技术的实施流程,特别是DEL库构建和亲和筛选方法的最新研究进展,展示了利用DEL技术筛选开发的最新亲和配体分子,并对DEL技术在生命科学领域的应用前景作了展望。     

Cbl Ubiquitin Ligases Control B Cell Exit from the Germinal-Center Reaction

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Precursor Frequency and Affinity Determine B Cell Competitive Fitness in Germinal Centers,Tested with Germline-Targeting HIV Vaccine Immunogens

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B Cell Receptor and CD40 Signaling Are Rewired for Synergistic Induction of the c-Myc Transcription Factor in Germinal Center B Cells

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Functional characterization of specific IgE antibodies for tetanus toxoid

Summary The specific IgE response that appears in subjects immunized with tetanus toxoid does not induce hypersensitivity reactions at subsequent immunizations. The type I immune response, therefore, was studied bothin vivo andin vitro, in 11 subjects who had specific IgE antibodies for tetanus toxoid. The results showed that: 1. the specific IgE antibodies are heterogeneous regarding their affinity for the mast cell and basophil receptors; 2. the specific IgG antibodies for tetanus toxoid, at serum concentrations, are not able to interfere with thein vitro specific basophil degranulation; 3. in the PEG precipitare there are aggregates of specific IgE antibodies for tetanus toxoid.In vitro, these molecular aggregates are not able to sensitize the basophil cells.     

α-突触核蛋白与Cu~(2+)相互作用的研究进展

帕金森病是一种慢性中枢神经系统退行性疾病,其主要的病理特征是黑质致密部多巴胺能神经元丢失,残存神经元胞质中出现路易小体,其主要成分是异常聚集的α-synuclein蛋白(α-突触核蛋白)。α-synuclein的聚集与多种因素有关,其中金属离子与α-synuclein结合可导致蛋白构象发生变化引起蛋白发生聚集。近年的研究发现,Cu2+能够特异地结合α-synuclein蛋白,并诱导α-synuclein的聚集。该文就Cu2+与α-synuclein相互作用的的结合位点、结合模式以及Cu2+在α-synuclein毒性形式中可能发挥的作用作一综述。     

Structural and Binding Studies of SAP-1 Protein With Heparin

SAP-1 is a low molecular weight cysteine protease inhibitor (CPI) which belongs to type-2 cystatins family. SAP-1 protein purified from human seminal plasma (HuSP) has been shown to inhibit cysteine and serine proteases and exhibit interesting biological properties, including high temperature and pH stability. Heparin is a naturally occurring glycosaminoglycan (with varied chain length) which interacts with a number of proteins and regulates multiple steps in different biological processes. As an anticoagulant, heparin enhances inhibition of thrombin by the serpin antithrombin III. Therefore, we have employed surface plasmon resonance (SPR) to improve our understanding of the binding interaction between heparin and SAP-1 (protease inhibitor). SPR data suggest that SAP-1 binds to heparin with a significant affinity (K_D = 158 nm ). SPR solution competition studies using heparin oligosaccharides showed that the binding of SAP-1 to heparin is dependent on chain length. Large oligosaccharides show strong binding affinity for SAP-1. Further to get insight into the structural aspect of interactions between SAP-1 and heparin, we used modelled structure of the SAP-1 and docked with heparin and heparin-derived polysaccharides. The results suggest that a positively charged residue lysine plays important role in these interactions. Such information should improve our understanding of how heparin, present in the reproductive tract, regulates cystatins activity.