The interaction of platelet factor four and glycosaminoglycans.
The interaction of platelet factor four and glycosaminoglycans.
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DOI：
10.1016/0003-9861(85)90049-9
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发表时间：
1985-07
影响因子：
3.9
通讯作者：
J. Loscalzo;B. Melnick;R. Handin
中科院分区：
文献类型：
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作者：
J. Loscalzo;B. Melnick;R. Handin
血小板因子4（PF-4）与糖胺聚糖（GAG）的相互作用进行了评价，使用荧光光谱，放射性配体结合试验，并利用抗凝血酶III和因子Xa的功能测定。在这些研究中，我们（i）表征了PF-4与几种形式的肝素和硫酸葡聚糖的结合参数;（ii）检查了支持PF-4结合的这些糖胺聚糖的结构特征;（iii）检查了PF-4羧基末端选择性消化对结合的影响。PF-4与未分级猪肠粘膜肝素（<Mr>）= 11，000）的结合是特异性且可饱和的，PF-4与肝素的摩尔化学计量比约为4：1，表观估计Kd为3 × 10 - 8 m。肝素组分（<Mr>）= 6，000），对与PF-4结合的抗凝血酶III具有低或高亲和力，表观Kd相似。PF-4也与硫酸葡聚糖（<Mr>= 22，500）结合，估计表观Kd为6 × 10− 8，摩尔化学计量比约为16：1。羧肽酶Y（CP-Y）消化PF-4逐渐降低GAG结合。消化30分钟后，此时所有羧基末端丝氨酸和谷氨酸、两个亮氨酸和大约四分之一的四个赖氨酸都被去除，肝素结合的IC 50从10 nm变为150 nm。这些研究证明了GAG聚合物大小和硫酸化程度对PF-4结合的亲和力和化学计量的影响，以及PF-4的羧基末端氨基酸对结合天然和合成GAGS的至关重要性。
The interaction of platelet factor four (PF-4) with glycosaminoglycans (GAG) was evaluated using fluorescence spectroscopy, a radioligand binding assay, and a functional assay utilizing antithrombin III and factor Xa. In these studies, we have (i) characterized the binding parameters for PF-4 to several forms of heparin and to dextran sulfate; (ii) examined the structural features of these glycosaminoglycans which support PF-4 binding; and (iii) examined the effects of selective digestion of the carboxy terminus of PF-4 on binding. The binding of PF-4 to unfractionated porcine intestinal mucosal heparin (<Mr>) = 11,000) was specific and saturable, with a molar stoichiometry of PF-4 to heparin of approximately 4:1 and an apparent estimatedKdof 3 × 10−8m. Heparin fractions (<Mr>) = 6,000) with either low or high affinity for antithrombin III bound to PF-4 with a similar apparentKd. PF-4 also bound to dextran sulfate (<Mr> = 22,500) with an estimated apparentKdof 6 × 10−8mand a molar stoichiometry of approximately 16:1. Carboxypeptidase Y (CP-Y) digestion of PF-4 progressively decreased GAG binding. After 30 min of digestion, by which time all of the carboxyterminal serine and glutamate, both of the two leucines, and approximately one-quarter of the four lysines were removed, the IC50for heparin binding shifted from 10 to 150 nm. These studies demonstrate the effect of GAG polymer size and degree of sulfation on the affinity and stoichiometry of PF-4 binding, and the critical importance of the carboxy-terminal amino acids of PF-4 for binding to natural and synthetic GAGS.