Ostrem J A, al-Obeidi F, Safar P, Safarova A, Stringer S K, Patek M, Cross M T, Spoonamore J, LoCascio J C, Kasireddy P, Thorpe D S, Sepetov N, Lebl M, Wildgoose P, Strop P
Selectide Corporation, Tucson, Arizona 85737, USA.
Biochemistry. 1998 Jan 27;37(4):1053-9. doi: 10.1021/bi971147e.
A series of low molecular weight peptide inhibitors of factor Xa, unrelated to any previously described, was identified by screening a combinatorial peptide library composed of L-amino acids. The minimal inhibitory sequence is a tripeptide, L-tyrosinyl-L-isoleucyl-L-arginyl, which competitively inhibits the hydrolysis of small chromogenic substrates by factor Xa but binds in an orientation which prevents a productive nucleophilic attack by serine 195 of the catalytic triad on the carbonyl carbon of the carboxyterminal arginine. The initial leads identified in an octamer combinatorial peptide library ranged in potency from 4 to 15 microM. These peptides were modified into peptide mimetics with a greater than 1000-fold increase in potency while retaining unusual selectivity for factor Xa over the related serine proteases thrombin, factor VIIa/tissue factor, plasmin, activated protein C, kallikrein, and trypsin. One of the most potent analogues, SEL 2711, with a Ki of 0.003 microM for factor Xa and 40 microM for thrombin, is active in in vitro and ex vivo coagulation assays, suggesting the potential application of these inhibitors in anticoagulant therapy.
通过筛选由L-氨基酸组成的组合肽文库，鉴定出了一系列与先前描述的任何因子Xa低分子量肽抑制剂均无关的抑制剂。最小抑制序列是一个三肽，L-酪氨酰-L-异亮氨酰-L-精氨酰，它竞争性抑制因子Xa对小分子生色底物的水解，但以一种阻止催化三联体中的丝氨酸195对羧基末端精氨酸的羰基碳进行有效亲核攻击的方向结合。在一个八聚体组合肽文库中鉴定出的最初先导物的效力范围为4至15微摩尔。这些肽被修饰成肽模拟物，效力提高了1000倍以上，同时对因子Xa相对于相关丝氨酸蛋白酶凝血酶、因子VIIa/组织因子、纤溶酶、活化蛋白C、激肽释放酶和胰蛋白酶仍保持异常的选择性。其中一种最有效的类似物SEL 2711，对因子Xa的Ki为0.003微摩尔，对凝血酶的Ki为40微摩尔，在体外和体内凝血试验中均有活性，表明这些抑制剂在抗凝治疗中有潜在应用。
