High-specificity affinity reagents for the detection of glycan sialylation

描述（由申请方提供）：聚糖具有几种独特的性质，使其作为疾病生物标志物的开发具有吸引力。首先，它们在细胞表面的位置使它们成为细胞相互作用的第一个接触点，因此它们在控制正常代谢过程中至关重要，相反，它们作为病原体粘附受体发挥作用。其次，在正常状态下不存在或含量低的特定聚糖结构在疾病状态下增殖或改变其序列。最后，糖基化的变化可以在许多蛋白质中发现，包括那些高度丰富的蛋白质。因此，聚糖结构（如末端唾液酸）的正常水平的变化可能是疾病状态的标志。需要新的高度特异性的试剂，以克服目前在发现和开发疾病相关聚糖方面的限制。使用结构导向 通过基因操作，我们将从S.肺炎球菌转化为用于检测糖肽和糖蛋白的唾液酸修饰的高特异性亲和试剂。由于这种蛋白质具有凝集素样性质，但来源于酶，因此被称为“Lectenz（r）"。NanB Lectenz（r）解决了疾病糖标记物检测的关键需求：即，一种稳定且易于生产的β 3-连接唾液酸特异性试剂。该试剂可用于样品富集的亲和基质中，其与现有的基于MS的方法结合可提供连接信息。它也可以用于组织学研究或蛋白质印迹等。Lectenz（r）提供了许多优于植物凝集素的优点：它们被设计成高亲和力，但保留了内源酶的精致底物特异性，它们可以有效地产生，并且对于人类同源物具有低毒性的体内应用潜力。尽管Lectenz（r）开发的某些方面与抗体进化的那些方面平行，但Lectenz（r）具有使用具有所需特异性的蛋白质幼稚模板的巨大好处。

DESCRIPTION (provided by applicant): Glycans have several distinct properties that make their development as disease biomarkers appealing. Firstly, their location on cell surfaces makes them the first point of contact for cellular interactions, and thus they are crucial in the control of normal metabolic processes, and conversely, they function as pathogen adhesion receptors. Secondly, specific glycan structures that are not present, or are in low amounts in normal state, proliferate or alter their sequence in disease states. And, lastly, changes in glycosylation may be found in many proteins, including those that are highly abundant. Thus changes in the normal levels of glycan structures, such as terminal sialic acid, may be markers of disease states. New highly-specific reagents are required in order to overcome current limitations in the discovery and exploitation of disease-related glycans. Using structurally-guided genetic manipulations, we will convert the NanB sialidase from S. pneumococcus into a high-specificity affinity reagent for the detection of sialic acid modifications of glycopeptides and glycoproteins. Because such a protein has lectin-like properties, but is derived from an enzyme, it is called a "Lectenz(r)". A NanB Lectenz(r) addresses a key need in disease glycomarker detection: namely, a robust and easy to produce reagent specific for �3-linked sialic acid. This reagent could be employed in an affinity matrix for sample enrichment, which in conjunction with existing MS based methods could provide linkage information. It could also be employed in histological studies, or Western blots, etc. Lectenz(r) offer numerous advantages over plant lectins: they are engineered to be high affinity and yet retain the exquisite substrate specificityof the endogenous enzyme, they may be efficiently produced, and for human homologues have the potential to be employed in vivo with low toxicity. Whereas some aspects of Lectenz(r) development parallel those of antibody evolution, Lectenz(r) have the tremendous benefit of employing a protein naive template that has the desired specificity.