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AA Hasan, WS Chang and AZ Budzynski
Department of Biochemistry, Temple University School of Medicine,
Philadelphia, PA 19140.
To explore whether fibrin fragments have binding affinity for the
tissue-type plasminogen activator (t-PA) molecule, the interactions were
studied of (DD)E complex and fragments DD, E1, and E3 with one- chain and
two-chain t-PA. For this purpose, a solid-phase binding assay was developed
using microtiter plates with nitrocellulose filters. It was found that
(DD)E complex and fragments DD and E3 retained the t-PA binding function of
the parent fibrin molecule, thus demonstrating that t-PA binds to both the
D and E domains of fibrin. Unexpectedly, fragment E1 did not bind t-PA.
Fibrin fragments had different binding properties for one-chain and
two-chain t-PA. (DD)E complex had the highest and fragment E3 the lowest
affinity for one-chain t-PA, both binding curves being consistent with one
class of binding sites. However, binding of the fragments with two-chain
t-PA was distinguished by more than one class of binding sites, with
fragment E3 having the highest affinity for this form of the activator.
epsilon-Aminocaproic acid, even at 50 mmol/L concentration, had only
minimal effect on binding of (DD)E complex or fragment DD to either
one-chain or two- chain t-PA. The potentiating effect of fibrin fragments
on plasminogen activation by t-PA was measured by a chromogenic substrate
assay. Fragment DD was the most effective stimulator of plasminogen
activation by t-PA. In conclusion, (DD)E complex and fragment DD retained
most of the regulatory functions of fibrin, which included t-PA binding and
t- PA-mediated acceleration of plasminogen activation to plasmin.
This article has been cited by other articles:
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| Copyright © 1992 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
