The Solution Structure of Heparan Sulfate Differs from That of Heparin IMPLICATIONS FOR FUNCTION (Retracted Article)
The Solution Structure of Heparan Sulfate Differs from That of Heparin IMPLICATIONS FOR FUNCTION (Retracted Article)
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DOI：
10.1074/jbc.m111.226027
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发表时间：
2011-07-15
影响因子：
4.8
通讯作者：
Perkins, Stephen J.
中科院分区：
文献类型：
--
作者：
Khan, Sanaullah;Rodriguez, Elizabeth;Perkins, Stephen J.
高度硫酸化的多糖肝素和硫酸乙酰肝素（HS）在生理和病理生理过程的调节中起着关键作用。尽管它的重要性，没有分子结构的自由HS已报告到现在。通过结合分析超离心，小角X射线散射，和约束散射模型最近用于肝素，我们分析了8个纯化的HS片段的聚合度6-18（dp 6-dp 18）和dp 24，对应于硫酸乙酰肝素的主要未硫酸化的GlcA-GlcNAc域的溶液结构。与肝素不同，HS dp 6-dp 24的沉降系数s（20，w）显示出较小的转子速度依赖性，其中测定了0.82-1.26 S（吸收光学）和1.05-1.34 S（干涉光学）的相似s（20，w）值。HS dp 6-dp 24的相应的X射线散射测量给出了1.03至2.82 nm的回转半径（R-G）值，0.31至0.65 nm的横截面回转半径（R-XS）值，以及3.0至10.0 nm的最大长度（L）。这些数据表明，HS具有比肝素更长和更弯曲的结构。从5000-8000个构象随机化的HS结构开始的约束散射建模给出了最佳拟合的dp 6-dp 16分子结构，其比肝素中的等效物更长且更弯曲。HS dp 18或dp 24没有得到拟合，表明它们具有更高的灵活性。我们的结论是，HS显示出一个扩展的弯曲构象，这是显着不同的肝素。这种差异归因于不同的主要单糖序列和HS的硫酸化减少，表明与肝素相比，HS可能与蛋白质发生不同的相互作用。
The highly sulfated polysaccharides heparin and heparan sulfate (HS) play key roles in the regulation of physiological and pathophysiological processes. Despite its importance, no molecular structures of free HS have been reported up to now. By combining analytical ultracentrifugation, small angle x-ray scattering, and constrained scattering modeling recently used for heparin, we have analyzed the solution structures for eight purified HS fragments degree of polymerization 6-18 (dp6-dp18) and dp24, corresponding to the predominantly unsulfated GlcA-GlcNAc domains of heparan sulfate. Unlike heparin, the sedimentation coefficient s(20,w) of HS dp6-dp24 showed a small rotor speed dependence, where similar s(20,w) values of 0.82-1.26 S (absorbance optics) and 1.05-1.34 S (interference optics) were determined. The corresponding x-ray scattering measurements of HS dp6-dp24 gave radius of gyration (R-G) values from 1.03 to 2.82 nm, cross-sectional radius of gyration (R-XS) values from 0.31 to 0.65 nm, and maximum lengths (L) from 3.0 to 10.0 nm. These data showed that HS has a longer and more bent structure than heparin. Constrained scattering modeling starting from 5000-8000 conformationally randomized HS structures gave best fit dp6-dp16 molecular structures that were longer and more bent than their equivalents in heparin. No fits were obtained for HS dp18 or dp24, indicating their higher flexibility. We conclude that HS displays an extended bent conformation that is significantly distinct from that for heparin. The difference is attributed to the different predominant monosaccharide sequence and reduced sulfation of HS, indicating that HS may interact differently with proteins compared with heparin.