PLATELET RECEPTOR RECOGNITION DOMAIN ON THE GAMMA-CHAIN OF HUMAN-FIBRINOGEN AND ITS SYNTHETIC PEPTIDE ANALOGS
PLATELET RECEPTOR RECOGNITION DOMAIN ON THE GAMMA-CHAIN OF HUMAN-FIBRINOGEN AND ITS SYNTHETIC PEPTIDE ANALOGS
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DOI：
10.1021/bi00433a025
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发表时间：
1989-04-04
期刊：
影响因子：
2.9
通讯作者：
HAWIGER, J
中科院分区：
文献类型：
--
作者：
KLOCZEWIAK, M;TIMMONS, S;HAWIGER, J
我们以前已经表明，识别活化的人血小板上的受体的结构域位于人纤维蛋白原γ上。残基400和411之间的链[Kloczewiak，M.，蒂蒙斯，S.，和Hawigar，J.（1984）Biochemistry 23，1767]。为了研究γ-半乳糖苷酶的这一片段的结构之间的相关性，链及其对ADP活化的人血小板上的受体的反应性，我们设计了一系列类似物，其在12个位置中的9个位置上含有替换。正常His 400-His 401序列被Ala-Ala的双取代使十二肽的抑制效力降低3倍。当Lys 406被替换为Arg时，十二肽的抑制效力降低了15倍。另一方面，用Arg取代Ala 408使十二肽的抑制效力增加6倍。当Val 411被亮氨酸或半胱氨酸或酪氨酸取代时，观察到十二肽对血小板受体的反应性急剧下降。当Val 411被苯丙氨酸取代时，注意到反应性降低3倍。羧基末端Val 411的酰胺化也导致十二肽反应性显着降低。保留7个残基（His 400，His 401，Leu 402，Lys 406，Gln 407和Val 411），用非极性亮氨酸或极性丝氨酸取代中间的5个氨基酸，增加或减少十二肽的疏水性，使其抑制效力降低16倍以上。针对人纤维蛋白原γ的兔抗体Fab片段包含残基385-411的链肽抑制50%的125 I-纤维蛋白原结合，其化学计量比为125 I-纤维蛋白原的2：1。在体内输注十二肽与天然序列到兔肠系膜动脉引起可逆的抑制止血血小板血栓形成。
We have shown previously that the domain recognizing receptors on activated human platelets is located on the human fibrinogen .gamma. chain between residues 400 and 411 [Kloczewiak, M., Timmons, S., Lukas, T.J. and Hawigar, J. (1984) Biochemistry 23, 1767]. To study the correlation between the structure of this segment of the .gamma. chain and its reactivity toward receptors on ADP-activated human platelets, we designed a series of analogues containing replacements at 9 out of 12 positions. A double substitution of the normal His400-His401 sequence by Ala-Ala reduced the inhibitory potency of the dodecapeptide 3-fold. When Lys406 was replaced by Arg, the inhibitory potency of the dodecapeptide decreased 15 times. On the other hand, substitution of Ala408 with Arg increased the inhibitory potency of the dodecapeptide 6-fold. A drastic decrease in the reactivity of the dodecapeptide toward platelet receptors was observed when Val411 was replaced by leucine or cysteine or tyrosine. A 3-fold decrease in reactivity was noted when Val411 was substituted with phenylalanine. Amidation of the carboxy-terminal Val411 also produced a significant decrease in dodecapeptide reactivity. With seven residues (His400, His401, Leu402, Lys406, Gln407, and Val411) preserved, substitution of the intervening five amino acids with nonpolar leucine or polar serine, increasing or decreasing the hydrophobicity of the dodecapeptide, reduced more than 16-fold its inhibitory potency. Rabbit antibody Fab fragments directed against the human fibrinogen .gamma.-chain peptide encompassing residues 385-411 inhibited 50% of 125I-fibrinogen binding at a 2:1 stoichiometry with regard to 125I-fibrinogen. In vivo infusion of dodecapeptide with a native sequence into rabbit mesenteric artery caused reversible inhibition of hemostatic platelet thrombus formation.