The chemical modification of lysine residues in human alpha-thrombin has been used to study the interaction of thrombin with human platelets. Phosphopyridoxylation of thrombin using pyridoxal 5'-phosphate (pyridoxal-P) has been shown to inhibit the fibrinogen clotting activity of thrombin but not the catalytic activity (Griffith, M. J. J. Biol. Chem. 254, 3401-3406). Phosphopyridoxylation resul...

Blood-brain barrier dysfunction (BBB) is an important factor to the development of epilepsy and its behavioral comorbidities. Disruption integrity accompanied by ingress blood components, including thrombin, into cerebrospinal fluid. The effect thrombin mediated mainly through major receptor, protease-activated receptors 1 (PAR1). Using lithium-pilocarpine model seizures, we show that downregul...

We describe here the alteration of thrombin specificity induced by its interaction with glycocalicin. Glycocalicin is the external part of platelet glycoprotein Ib alpha (GPIb alpha) and contains binding sites for von Willebrand factor and thrombin. Taking advantage of its solubility, we have used glycocalicin in competition assays on various thrombin activities. Glycocalicin did not inhibit ch...

Studies with various thrombin derivatives have shown that initiation of cell proliferation by thrombin requires two separate types of signals: one, generated by high affinity interaction of thrombin or DIP-thrombin (alpha-thrombin inactivated at ser 205 of the B chain by diisopropylphosphofluoridate) with receptors and the other, by thrombin's enzymic activity. To further study the role of high...

Thrombin is a serine proteinase that plays a fundamental role in coagulation. In this study, we address the effects of ligand site recognition by alpha-thrombin on conformation and energetics in solution. Active site occupation induces large changes in secondary structure content in thrombin as shown by circular dichroism. Thrombin-D-Phe-Pro-Arg-chloromethyl ketone (PPACK) exhibits enhanced equ...

It has previously been reported that murine macrophages can respond chemotactically and mitogenically to the serine proteinase thrombin. There is a similar response in these macrophages to catalytically inactivated thrombin or to peptide fragments of the thrombin B-chain [Bar-Shavit, Kahn, Mann and Wilner (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 976-980]. However, the existence of a non-proteol...

The clearance of (125)I-thrombin and diisopropylphosphoryl-(125)I-thrombin (DIP-thrombin) from the circulation in rabbits was studied. When given either intraarterially or intravenously, DIP-thrombin, which is active-site blocked, was approximately 90% cleared from the circulation by 1 min, the time of earliest sampling, indicating a large first-pass effect. DIP-thrombin given intravenously is ...

OBJECTIVE Thrombin, a serine protease, plays an important role in thrombosis as well as other cellular and developmental processes. In this study, we investigated the ability of a novel thrombin-activatable molecular probe to provide in vivo images of thrombin activity in experimental thrombi. METHODS AND RESULTS The thrombin probe consists of a near-infrared (NIR) fluorochrome attached to a ...

Thrombin is the central enzyme of haemostasis. Information on the production and inhibition of thrombin in plasma is important for evaluating the state of the coagulation system. Measurement of thrombin generation in plasma using small oligopeptide chromogenic substrates gives rise to a signal that not only reflects the enzymatic activity of free thrombin, but also contains a contribution of th...