Structures of thrombin retro-inhibited with SEL2711 and SEL2770 as they relate to factor Xa binding.
Structures of thrombin retro-inhibited with SEL2711 and SEL2770 as they relate to factor Xa binding.
复制标题
凝血酶的结构受到 SEL2711 和 SEL2770 的逆向抑制，因为它们与 Xa 因子结合有关。
DOI：
10.1107/s0907444999000359
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Tulinsky,A
中科院分区：
文献类型：
--
作者：
Mochalkin,I;Tulinsky,A
大多数凝血酶活性位点抑制剂与残基Ser 214-Gly 216形成短的反平行β链。然而，Selectide Corp.抑制剂SEL 2711和SEL 2770以逆向方式结合凝血酶，产生与其他逆向结合抑制剂类似的具有Ser 214-Gly 216的平行β链。已确定与SEL 2711和SEL 2770（与二元凝血酶-水蛭素复合物同构）复合的凝血酶-水蛭素的晶体结构，并在9.0-2.1 μ m分辨率范围内将其细化至最终R值分别为16.5%和16.7%。 SEL 2711和SEL 2770复合物的结构分别含有131和104个水分子，两者都对应于大于0.5的占位率。SEL 2711和SEL 2770的1 -4-脒基苯基丙氨酰残基固定在S1特异性位点，利用脒基N原子和Asp 189侧链O原子之间有利的离子和氢键相互作用。凝血酶的Glu 192残基采用延伸构象，这允许抑制剂的P2反向结合位置中的l-环己基甘氨酰残基占据与凝血酶血小板受体肽结合的凝血酶中的P3天冬氨酸类似的位点。两种抑制剂的N-末端乙酰基位于S2亚位点，而SEL 2711的1 -3-吡啶基-（3-甲基）-丙氨酰和SEL 2770的1-（N，N-二甲基）赖氨酸占据凝血酶-PPACK复合物中d-PheProArg氯甲基酮（PPACK）的S3 d-Phe亚位点。SEL 2711的两个C-末端残基（亮氨酸和脯氨酸）指向溶剂，在凝血酶复合物中没有电子密度。SEL 2770的那些也位于溶剂中，但令人惊讶地产生具有高B值的弱电子密度（B = 50 μ 2）。 由于Selectide抑制剂对因子Xa的特异性高约104倍，因此对后者的逆向结合建模表明，选择性可能是因子Xa的S3-S4结合亚位点中抑制剂相互作用的结果。
Most thrombin active-site inhibitors form a short antiparallel β-strand with residues Ser214–Gly216. However, the Selectide Corp. inhibitors SEL2711 and SEL2770 bind to thrombin in a retro fashion, making a parallel β-strand with Ser214–Gly216 similar to other retro-binding inhibitors. The crystallographic structures of thrombin–hirugen complexed with SEL2711 and SEL2770, which are isostructural with the binary thrombin–hirugen complex, have been determined and refined in the 9.0–2.1 Å resolution range to final R values of 16.5 and 16.7%, respectively. The structures of the SEL2711 and SEL2770 complexes contain 131 and 104 water molecules, respectively, both of which correspond to occupancies of greater than 0.5. The l-4-amidinophenylalanyl residues of SEL2711 and SEL2770 are fixed at the S1 specificity site, utilizing favorable ionic and hydrogen-bonding interactions between the N atoms of the amidino group and the side-chain O atoms of Asp189. The Glu192 residue of thrombin adopts an extended conformation, which allows the l-cyclohexylglycyl residue in the P2 retro-binding position of the inhibitors to occupy a similar site to the P3 aspartate in thrombin platelet-receptor peptides bound to thrombin. The N-terminal acetyl group of both inhibitors is located in the S2 subsite, while the l-3-pyridyl-(3-methyl)-alanyl of SEL2711 and the l-(N,N-dimethyl)lysine of SEL2770 occupy the S3 d-Phe subsite of d-PheProArg chloromethyl ketone (PPACK) in the thrombin–PPACK complex. The two C-terminal residues of SEL2711 (leucine and proline) point into the solvent and have no electron density in the thrombin complex. Those of SEL2770 are also positioned into the solvent, but surprisingly produce weak electron density with high B values (〈B〉 = 50 Å2). Since the Selectide inhibitors are about 104 times more specific for factor Xa, modeling retro-binding to the latter suggests that the selectivity can be a consequence of interactions of the inhibitors in the S3–S4 binding subsites of factor Xa.