التفاصيل البيبلوغرافية
| العنوان: |
Study of tissue-type plasminogen activator binding sites on fibrin using distinct fragments of fibrinogen. |
| المؤلفون: |
Grailhe, Patrick, Nieuwenhuizen, Willem, Anglés-Cano, Eduardo |
| المصدر: |
European Journal of Biochemistry; 2/1/94, Vol. 219 Issue 3, p961, 7p |
| مصطلحات موضوعية: |
PLASMINOGEN activators, FIBRINOGEN, AMINO acids |
| مستخلص: |
It is well established that tissue-type plasminogen activator (t-PA) binds to the D region of fibrin(ogen) and that two distinct CNBr fragments of fibrinogen (FCB), FCB-2 and FCB-5, comprising parts of this region, stimulate plasminogen activation by t-PA. In the present work, ligandbinding studies were performed to characterize the interactions between t-PA and the corresponding fibrin regions using a well defined model of a fibrin surface and both FCB-2 and FCB-5 in liquid and solid phase. Binding isotherms showed a characteristic Langmuir adsorption saturation profile. The dissociation constants determined for the binding of t-PA to immobilized FCB-2 (K[SUBd]= 0.70 ± 0.10 nM) and FCB-5 (K[SUBd] = 0.47 ± 0.08 nM) were of the same order of magnitude as the K[SUBd] for fibrin binding (K[SUBd] = 1±0.2 nM). The specificity of the binding was demonstrated by the ability of soluble FCB-2 and FCB-5 to inhibit t-PA binding to solid-phase fibrin (K, = 3.3 [tM and 6.4 gM, respectively). The binding of t-PA to fibrin and to immobilized FCB-2 was partially inhibited by the lysine analogue 6-aminohexanoic acid (K[SUBi] = 123 ± 47 [tM and 364 [tM, respectively) but was not modified by carboxypeptidase B, thus indicating involvement of internal lysine residues. Removal of lysine residues by treatment with, successively, plasmin and carboxypeptidase B, produced only a partial inhibition of t-PA binding, thus confirming the existence of both a lysine-dependent and a lysine-independent mechanism of binding of t-PA to both fibrin and FCB-2. In contrast, the binding of t-PA to FCB-5 was not significantly affected by 6-aminohexanoic acid. Altogether, these data indicate that the mechanism of binding of t-PA to fibrin involves mainly a lysine-independent interaction with the D region which is contributed by sequences present in FCB-5 and FCB-2; contribution to binding by a lysine-dependent interaction was detected only in FCB-2 and is probably of minor relevance as suggested by the limited effect of 6-aminohexanoic acid. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
Complementary Index |
