Pharmaceutical Research Department of CMC Research Center, Mitsubishi Tanabe Pharma Corporation, 3-16-89, Kashima, Yodogawa-ku, Osaka 532-8505, Japan.
Int J Pharm. 2012 Nov 15;438(1-2):296-301. doi: 10.1016/j.ijpharm.2012.09.016. Epub 2012 Sep 15.
A dodecapeptide (γ400-411) derived from a fibrinogen γ-chain carboxyl-terminal sequence recognizes specifically the active form of GPIIb/IIIa on the surface of activated platelets. For the purpose of efficient hemostasis, we previously developed ADP-encapsulated liposomes modified with human-dodecapeptide (HHLGGAKQAGDV, human-H12). On the other hand, the amino-acid sequence of H12 from rats is HHMGGSKQVGDM, having only 67% homology to that from humans. Here, we investigated the ability of rat-H12 in comparison with human-H12 to bind to platelets. Firstly, rat platelets were activated with phorbol-12-myristate-13-acetate (PMA), and the activation was confirmed by flow cytometry. Next, we evaluated the dissociation constant (K(d)) of human-H12 and rat-H12 for dissociation from rat platelets by using FACS. As a result, the K(d) of human-H12 and rat-H12 with respect to rat platelets was 2.78 ± 0.21 and 2.91 ± 0.22 μM, respectively. Furthermore, H12 from both species inhibited quite similarly the aggregation of rat platelets in platelet-rich plasma (PRP). These results suggest that H12 from different species with different amino acid sequences interacts similarly with GPIIb/IIIa on platelets.
一种源自纤维蛋白原 γ 链羧基末端序列的十二肽（γ400-411）特异性识别激活血小板表面的活性形式的 GPIIb/IIIa。为了实现有效的止血，我们之前开发了用人类十二肽（HHLGGAKQAGDV，人-H12）修饰的包载 ADP 的脂质体。另一方面，大鼠 H12 的氨基酸序列为 HHMGGSKQVGDM，与人类的同源性仅为 67%。在这里，我们研究了大鼠-H12 与人类-H12 结合血小板的能力。首先，用佛波醇-12-肉豆蔻酸-13-醋酸酯（PMA）激活大鼠血小板，并通过流式细胞术确认激活。接下来，我们通过 FACS 评估了人-H12 和大鼠-H12 从大鼠血小板上解离的解离常数（Kd）。结果，人-H12 和大鼠-H12 与大鼠血小板的 Kd 值分别为 2.78±0.21 和 2.91±0.22 μM。此外，两种物种的 H12 均能相当抑制富含血小板的血浆（PRP）中大鼠血小板的聚集。这些结果表明，具有不同氨基酸序列的不同物种的 H12 与血小板上的 GPIIb/IIIa 相互作用相似。
