凝集素&糖生物学试剂

  凝集素概述：

凝集素（Lectin）是指一种从各种植物，无脊椎动物和高等动物中提纯的糖蛋白或结合糖的蛋白。其具有对某一种特异性糖基专一性结合的能力(类似于抗原-抗体反应)。因此，凝集素在生物识别（例如，细胞与蛋白识别）中发挥了重要的作用，例如：一些病毒利用凝集素将其附着在宿主细胞上、凝集素可识别某些致病真菌等。

随着多种生物技术手段不断发展，利用凝集素进行研究的新方法也逐渐崭露头角。除了传统的组织/细胞免疫实验、Western bloting、酶联免疫检测（ELISA）以及细胞培养等实验中的应用，凝集素也在更多新的领域，Flow Cytometry(细胞分型)、亲和层析、表面等离子体共振（SPR）等领域发挥其作用。目前，Vector Labs的凝集素产品已被美国国家糖组学功能研究中心(NCFG)指定为首选产品。

  凝集素应用：

  产品类别：

  热销凝集素举例：

详情请咨询 Vectorlabs 中国代理- 上海金畔生物科技

凝集素全能小帮手 — 5种方式助力糖生物学研究

糖蛋白（聚糖）以及生物结合物通过介导细胞与细胞间的相互作用，对生物机体发挥至关重要的作用。糖链结构的变化在许多疾病，包括肿瘤、糖尿病以及自身免疫性疾病等中发挥核心作用。但是，目前只有很小一部分的生物标志物是与细胞表面的糖蛋白相关。主要原因是单糖形成聚糖的方式多样性和复杂性，导致对复杂糖蛋白（例如，凝集素）结构的研究进展很慢。

凝集素（Lectin）一词源于拉丁语”legere”，意思是“选择”，指它们具有识别并结合不同碳水化合物结构的能力。但是，为什么这种特性使其在糖生物学上有如此应用前景呢?

随着生物标志物研究的不断发展，利用凝集素进行研究的新方法也逐渐崭露头角。本文总结了凝集素作为糖生物学研究工具的5种主要应用。

1.凝集素可灵活应用于组织/细胞免疫组化实验

To elicit biologically-relevant information about aberrant glycosylation, you need to visualize cell glycan distribution and its impact on morphology. Fortunately, lectins are compatible tools for molecular imaging protocols, such as immunohistochemistry (IHC) and immunofluorescence (IF), as the tissue staining protocols for antibodies are mostly valid for lectins. Both workflows are simple to implement, producing rapid results. 

In your IHC workflow, you can conjugate a lectin to enzymes (e.g., horseradish peroxidase) or haptens (e.g., biotin). The resulting lectin conjugate and appropriate substrate can be viewed under light microscopy or electron microscopy.  

Your other option for your IF workflow, label lectins with a fluorescent dye (e.g., fluorescein isothiocyanate (FITC)), which allows you to view glycan distribution with a fluorescent microscope. The use of lectins in IF has the added advantage of multiplexing, which allows you to use multiple fluorescent dyes to visualize multiple types of glycan chains in the same sample.

2.可实现使用最小的样本量进行高效的聚糖分析

Scanning a sample for multiple glycan sequences can be time consuming without high-throughput analysis methods. Lectins can provide time-saving and cost-effective analysis with the help of very small solid surfaces, such as microchips.  

Because you want a comprehensive glycan profiling of your sample, you need to detect as many different glycan structures as possible. Compared to antiglycan antibodies which have stringent specificity towards glycans, making them more time-consuming to use, lectins are more versatile in their binding patterns, meaning that one lectin can bind multiple glycans (1). This makes lectins more effective than antibodies as microarray tools.

3.无需糖链释放——直接进行聚糖检测

One of the advantages of lectins is their ability to detect glycans without the need to release them from their bioconjugates. Lectin blotting, based on western blotting, is a method that provides insight into glycan structures while they are still attached to their glycoproteins. Intact glycoproteins or glycolipids can be probed with lectins and there is no requirement for cleaving the whole complex. This also makes lectin blotting a promising tool for comparing glycosylation networks between control and test samples. For instance, researchers could demonstrate altered sialylation and fucosylation of N-glycans in colorectal cancer by comparing biofluid samples from cancer patients to those from healthy subjects (2).  

Lectin microarray is another method for rapid glycan detection that does not require glycan release. This allows you to detect and differentiate all possible disease-associated glycan isomers, aberrant sialic acid linkages, and terminal glycan structures within glycoproteins and glycolipids. For example, lectin microarray was used extensively to help researchers discover predictive biomarkers in several cancer types, such as colorectal (3) and gastric cancer (4).

4.可用于活细胞分析（Flow-Cytometry流式实验应用）

Understanding the correlation between specific glycan structures and cell characteristics is necessary for elucidating cell size, proliferation, and differentiation. To obtain biologically-relevant data, you should be able to work with live cells. The great news is that you can integrate fluorescently labelled lectins into flow cytometry protocols to perform live-cell imaging.  

The use of lectins in flow cytometry is advantageous because it offers an opportunity for quantitative analysis of glycan profiles in different cell subtypes. Lectins can help characterize cellular subpopulations even when a specific cell type is scarce in the overall cell population.  

The combination of lectins and flow cytometry led to many breakthroughs in stem cell research. Using lectins in flow cytometry, researchers were able to successfully characterize human embryonic stem cells (hESCs) and their differentiated progeny based on lectin-binding profiles. This also allowed them to isolate neural progenitor cells to analyze their role in brain development in detail (5).

5.可有效分离糖蛋白

Imagine wanting to analyze a specific aberrant glycoprotein in a sample, but the concentration of that particular glycoprotein is low. The solution is to run affinity chromatography to obtain eluates enriched with the glycoprotein of your interest.  

In lectin affinity chromatography, you can utilize the carbohydrate specificity of lectins by immobilizing them on your chromatography surface or matrix. Upon washing, the immobilized lectin binds the corresponding glycoprotein while the rest of the sample is washed away. The resulting elution is now suitable for mass spectroscopy and proteomics, generating further insight into the glycosylation mechanism of your protein. For example, lectin affinity chromatography played a significant role in the enrichment of core fucosylated peptides that are potential biomarkers in pancreatic cancer (6). 

结论

凝集素因其独特的理化特性使其成为研究细胞膜表面糖蛋白结构、功能及其对复杂疾病影响的理想工具。搭配糖样本制备平台和分析技术，可快速实现糖样本的分析，获得高度一致和可靠的数据结果。

目前，利用凝集素识别和分析糖蛋白样本的方法有很多，因此需要根据具体的实验需求选择最合适的产品。Vector Laboratories公司旨在通过对凝集素工作流程的详细阐述，为广大用于提供尽可能多的信息和支持。想要了解更多的凝集素产品的应用，可访问https://vectorlabs.com/browse/lectins 或咨询联系Vector Laboratories中国代理商上海金畔生物科技有限公司 http://www.jinpanbio.com/

凝集素和凝集原的三大区别

凝集素和凝集原看起来只有一字只差，实际上它们的区别还是很大的。为了帮助生物专业的伙伴或者是有一些对凝集素、凝集原感兴趣的科研朋友，本文特意整理了凝集素和凝集原的三大区别，供大家参考。

一、含义不同：

1、凝集原：凝集原附着在红细胞表面，是一种抗原。人类的红细胞含有两种凝集原，分别叫做A凝集原和B凝集原。

人类血清中则含有与凝集原对抗的两种凝集素，分别叫做抗A凝集素和抗B凝集素。 

2、凝集素：Lectin，凝集素是动物细胞和植物细胞都能够合成和分泌的、能与糖结合的蛋白质,在细胞识别和粘着反应中起重要作用,主要是促进细胞间的粘着。凝集素具有一个以上同糖结合的位点，因此能够参与细胞的识别和粘着,将不同的细胞联系起来。

二、组成物质不同：

1、凝集原：ABO血型系统凝集原是糖蛋白。蛋白部分是决定血型的抗原性物质，它是由11种氨基酸组成的多肽，其中以苏氨酸含量最多，其他还有丝氨酸、脯氨酸等。

多糖部分为粘多糖，包括D-半乳糖、L-岩藻糖、N-乙酰-D-氨基葡萄糖、N-乙酰-D-氨基半乳糖等。多糖部分是决定血型特异性的。

2、凝集素：从各种植物，无脊椎动物和高等动物中提纯的糖蛋白或结合糖的蛋白，因其能凝集红血球（含血型物质）。

常用的为植物凝集素（Phytoagglutin, PNA），通常以其被提取的植物命名，如刀豆素A（Conconvalina,ConA）、麦胚素（Wheat germ agglutinin, WGA）、花生凝集素（Peanut agglutinin, PNA）和大豆凝集素（Soybean agglutinin, SBA）等，凝集素是它们的总称。

三、存在地方不同：

凝集原在红细胞上，与血型相同；凝集素在血浆中，与血型相反。

红细胞上只有凝集原A的为A型血，其血清中有抗B凝集素；红细胞上只有凝集原B的为B型血，其血清中有抗A的凝集素；红细胞上A、B两种凝集原都有的为AB型血，其血清中无抗A、抗B凝集素。

红细胞上A、B两种凝集原皆无者为O型，其血清中抗A、抗B凝集素皆有。具有凝集原A的红细胞可被抗A凝集素凝集；抗B凝集素可使含凝集原B的红细胞发生凝集。

凝集素的应用：

一般认为细胞膜上特定的糖基可用以区别细胞的类型和反映细胞在分化、成熟和肿瘤细胞性变中的变化。

仅在某些特殊的例子，其细胞结合凝集素的性能可以预先估计，如双花扁豆素之于血型A物质的特异性，荆豆凝集素之于血型O物质2—L—岩藻糖的特异性。

然而在绝大多数情况下，关于由凝集素所识别的碳水化合物决定簇的种类，关于携带决定簇的分子的性质和机能，完全凭实验经验去发现。

如需了解更多，请咨询上海金畔生物