Factor IX Fukuoka. Substitution of ASN92 by His in the second epidermal growth factor-like domain results in defective interaction with factors VIIa/X.
Factor IX Fukuoka. Substitution of ASN92 by His in the second epidermal growth factor-like domain results in defective interaction with factors VIIa/X.
复制标题
因子 IX 福冈。
DOI：
10.1016/s0021-9258(20)80489-x
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
Sadaaki Iwanaga
中科院分区：
文献类型：
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作者：
Hitoshi Nishimura;Hiroyuki Takeya;Toshiyuki Miyata;K. Suehiro;T. Okamura;Yoshiyuki Niho;Sadaaki Iwanaga
B型福冈血友病是一种中重度出血性疾病，是一种自然发生的IX因子突变体。即使存在64%的IX因子抗原，患者的血浆仍有3%的凝血活性。纯化的突变蛋白被Xla因子、viia因子-组织因子复合体或RVV-X（来自罗素毒蛇毒液的x因子激活酶）正常切割，产生双链因子IXa。来源于福冈因子IX的赖氨酸内肽酶肽的氨基酸组成和序列分析表明，第二表皮生长因子（EGF）样结构域的Asn92已被His取代。因子IXa Fukuoka的活性位点通常能够结合对氨基苄脒和水解合成底物N α -苯氧羰基- l-精氨酸对硝基苯酯。福冈因子IXa形成的因子Xa仅为正常因子IXa的8%，即使在存在聚赖氨酸的情况下，在含有磷脂、Ca2+和因子VIIIa的系统中仅为正常的0.2%，从而表明突变体与因子VIIIa/X相互作用的功能缺陷。此外，在Ca2+、磷脂和因子VIIIa存在的情况下，因子IXa Fukuoka对因子X的催化效率（kcat/Km）仅为正常因子IXa的2.3%。这些结果表明，在因子IX Fukuoka的第二个egf样结构域92位的Asn-to-His取代将对因子IX与因子viia /X结合的特定构象状态产生不利影响。
Hemophilia B Fukuoka, a moderately severe bleeding disorder, is a naturally occurring mutant of factor IX. Plasma from our patient had 3% clotting activity even though 64% of factor IX antigen was present. The purified mutant protein was cleaved normally by factor Xla, factor VIIa-tissue factor complex, or RVV-X (factor X-activating enzyme from Russell's viper venom), yielding a two-chain factor IXa. Amino acid composition and sequence analyses of one of the lysyl endopeptidase peptides derived from factor IX Fukuoka revealed that Asn92 in the second epidermal growth factor (EGF)-like domain had been replaced by His. The active site of the factor IXa Fukuoka was normally competent for the incorporation of p-aminobenzamidine and for the hydrolysis of a synthetic substrate, N alpha-benzyloxycarbonyl-L-arginine p-nitrobenzyl ester. Factor Xa formation by factor IXa Fukuoka was only 8% of the normal factor IXa, even in the presence of polylysine, and only 0.2% of the normal in the system containing phospholipids, Ca2+, and factor VIIIa, thereby indicating a functional defect in interaction of the mutant with factors VIIIa/X. Furthermore, catalytic efficiency (kcat/Km) of factor IXa Fukuoka toward factor X in the presence of Ca2+, phospholipids, and factor VIIIa was only 2.3% of the normal factor IXa. These results suggest that an Asn-to-His substitution at position 92 in the second EGF-like domain of factor IX Fukuoka would have an untoward effect on the specific conformational state of factor IX for binding with factors VIIIa/X.