Sclerostin (SOST) is a glycoprotein having many important functions in the regulation of bone formation as a key negative regulator of Wnt signaling in bone. Surface plasmon resonance (SPR), which allows for a direct quantitative analysis of the label-free molecular interactions in real-time, has been widely used for the biophysical characterization of glycosaminoglycan (GAG)-protein interactions. In the present study, we report kinetics, structural analysis and the effects of physiological conditions (e.g., salt concentrations, Ca²⁺ and Zn²⁺concentrations) on the interactions between GAGs and recombinant human (rh) and recombinant mouse (rm) SOST using SPR. SPR results revealed that both SOSTs bind heparin with high affinity (rhSOST-heparin, K_D~36 nM and rmSOST-heparin, K_D~77 nM) and the shortest oligosaccharide of heparin that effectively competes with full size heparin for SOST binding is octadecasaccharide (18mer). This heparin binding protein also interacts with other highly sulfated GAGs including, disulfated-dermatan sulfate and chondroitin sulfate E. In addition, liquid chromatography-mass spectrometry was used to characterize the structure of sulfated GAGs that bound to SOST.

中文翻译：

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硬化蛋白与糖胺聚糖之间的相互作用

硬化蛋白（SOST）是一种糖蛋白，在骨形成方面具有许多重要功能，是骨中Wnt信号传导的关键负调节剂。表面等离振子共振（SPR）可实时定量分析无标记的分子相互作用，已被广泛用于糖胺聚糖（GAG）-蛋白质相互作用的生物物理表征。在本研究中，我们报告动力学，结构分析和在生理条件（例如，效果，盐浓度，钙²⁺和Zn ²⁺上的GAG和重组人（rh）之间的相互作用的浓度）和重组小鼠（RM）SOST使用SPR。SPR结果显示，两种SOST都以高亲和力结合肝素（rhSOST-肝素，K _D〜36纳米和rmSOST肝素，K _d〜77 nM）的中和肝素的最短寡糖有效地与全尺寸肝素SOST竞争结合是octadecasaccharide（18聚体）。该肝素结合蛋白还与其他高度硫酸化的GAG相互作用，包括二硫酸化皮肤素硫酸盐和硫酸软骨素E。此外，液相色谱-质谱法用于表征与SOST结合的硫酸化GAG的结构。