The Inhibition of Activated Factor X with Di:isopropyl Fluorophosphate

Leveson, James E.; Esnouf, M. P.

doi:10.1111/j.1365-2141.1969.tb01356.x

Cited by 33 publications

(10 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is not possible, however, to specify exactly the details of the mechanism. DFP is an irreversible inhibitor that binds the serine hydtoxyl at the active site of certain proteases, including several clotting enzymes (13,18,20,35). SBTI is also a serine protease inhibitor, but of a more specific nature.…”

Section: Discussionmentioning

confidence: 99%

A Mechanism of Migration Inhibition Involving Components of the Coagulation System

1976

View full text Add to dashboard Cite

Lymph from pigs given bacillus Calmette-Guérin (BCG) and stimulated in the drainage area of a cannulated lymph node with tuberculin (PPD) had potent in vitro macrophage migration inhibitory activity. A similar observation has previously been made in sheep by other workers. In the sheep, part of, and in the pig, almost all of, this inhibitory activity was produced, not by a factor resembling the so-called 'migration inhibitory factor', but by a mechanism involving a protease and fibrinogen. It is suggested that exudate cells, having potent coagulation-promoting activity, can promote the deposition of fibrin about themselves, and thus 'trapped' are unable to migrate.

show abstract

Section: Discussionmentioning

confidence: 99%

A Mechanism of Migration Inhibition Involving Components of the Coagulation System

1976

View full text Add to dashboard Cite

show abstract

“…Activated Factor X is a serine protease [28,46,55] capable of hydrolyzing Arg-X peptide bonds (see below) and N-substituted esters of arginine. Although few detailed studies on the hydrolysis of synthetic substrates by Factor Xa have been reported, the limited data available indicate that arginine esters are greatly preferred over lysine esters and that a small residue on the arginine α-amino group, such as an acetyl substituent, provides a better substrate than larger aromatic substituents such as benzoyl or tosyl ( Table 5).…”

Section: Substrate Specificity Of Factor Xamentioning

confidence: 99%

“…As the recent reports on prothrombin activation indicate that the Arg-Thr bond is cleaved before the Arg-Ile [22], it is interesting to ask if this small sequence difference is responsible for this order of bond cleavage in prothrombin. Activated Factor X can be inhibited by diisopropylfluorophosphate (iPr 2 P-F) [46,55], phenylmethanesulfonyl fluoride (PMSF) [46] and by soybean trypsin inhibitor [8,56,66]. Factor Xa apparently is not inhibited by the lima bean trypsin inhibitor [43].…”

Section: Substrate Specificity Of Factor Xamentioning

confidence: 99%

The Chemistry and Enzymology of Bovine Factor X

Henriksen¹,

Jackson²

2008

Semin Thromb Hemost

View full text Add to dashboard Cite

In the currently proposed schemes for blood coagulation [14,57,94], Factor X lies at the point of convergence of two distinguishable routes by which clotting is initiated. These two routes have been labeled the intrinsic and extrinsic coagulation pathways. Factor X exists in the plasma in an enzymatically inactive or zymogen form which, during coagulation, is activated to yield the proteolytic enzyme Factor Xa. Activation of Factor X via the intrinsic pathway requires only plasma-contained clotting factors, while the extrinsic pathway requires the participation of tissue-derived substances as well as plasma factors. The only known physiologic substrate for Factor Xa is another zymogen, prothrombin, which is activated to yield the protease thrombin. In turn, thrombin acts upon fibrinogen-yielding fibrin, which polymerizes to form a fibrin clot. Since the activation of Factor X is the first reaction common to both the intrinsic and extrinsic coagulation pathways, this activation process must be viewed as a key event in initiating thrombin formation as well as subsequent fibrin clot formation. Likewise, control of this activation process, as well as the consequent action of Factor Xa, becomes critical to regulating the formation and subsequent action of thrombin.A vitamin requirement for normal blood coagulation was first shown from the work of Dam [12], who named this vitamin "vitamin K." It was subsequently demonstrated that vitamin K was necessary for the formation of four specific plasma proteins, blood coagulation factors VII [52,77], IX [64,71,84], and X [3,42,84] in addition to prothrombin [89]. Of these proteins, in addition to Factor X itself, one is the substrate for Factor Xa, and the other two are responsible for Factor X activation.In the present discussion, we shall consider the isolation and characterization of Factor X, the process by which it is activated to yield Factor Xa, and finally the properties of Factor Xa as a proteolytic enzyme. This is not intended as a comprehensive review of all work in the field, but rather a presentation of what we believe to be salient features of Factor X chemistry and enzymology as well as recent developments in this field. The authors recognize that the development or our understanding of the chemistry and function of Factor X is the product of the contributions of many workers, some of whom may not be explicitly credited. We apologize for such omissions and would welcome their being called to our attention.

show abstract

“…§1734 solely to indicate this fact. iPr2P-F-inactivated factor Xa was prepared by incubating 1.0 mg of factor Xa, prepared as above, in 25 mM Tris'HCl buffer (pH 8.0) with 15 mM iPr2P-F in a total volume of 0.5 ml for 2.5 hr at 370C as described by Leveson and Esnouf (10). Treatment of factor Xa by iPr2P-F does not result in total loss of activity, but under these conditions we found that factor Xa lost >85% of its original activity.…”

mentioning

confidence: 99%

Inhibition of thromboxane A2 synthesis in human platelets by coagulation factor Xa.

Sinha¹,

Rao²,

Willis³

et al. 1983

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Factor X. binds to platelets provided that factor Va is present on the platelet surface, an interaction that results in a striking acceleration of the conversion of prothrombin to thrombin. Thrombin then initiates fibrin formation, induces platelet aggregation, and stimulates the intraplatelet synthesis of thromboxane A2 (TXA2). Addition of thrombin (2.4-14.4 nM) to plateletrich plasma increased the basal level of TXA2, measured as thromboxane B2, from <0.5 pmol per 108 platelets to (mean + SEM) 100 ± 22 and 250 ± 10 pmol per 108 platelets, respectively. Treatment of platelet-rich plasma with increasing concentrations of factor X. (1-12 nM) prior to the addition of thrombin progressively inhibited the production of TXA2. Thrombin (9.6 nM), which produced 93% of the maximal formation of TXA2, was inhibited 70% by factor Xa (10 nM). To identify which of these steps in thromboxane synthesis was inhibited by factor Xa, platelets labeled with [14C]arachidonic acid were exposed to thrombin and products of prostaglandin synthesis were separated by thin-layer chromatography. In contrast to the inhibition of TXA2 synthesis, prostaglandin E2 and prostaglandin F2a synthesis were not inhibited suggesting that neither phospholipase(s) nor cycloxygenase was involved. The inhibition of TXA2 formation by factor Xa could be reversed by increasing the molar ratio of thrombin to factor Xa to 5.5. Incubation of platelets with an IgG fraction of a human monoclonal antifactor V antibody, previously shown to inhibit factor X. binding, was found to block factor Xa inhibition of TXA2 synthesis. The inhibition of TXA2 synthesis requires the presence of the active site serine of factor Xa and is not specific for TXA2 formation induced by thrombin because it is also demonstrable when the agonist is ADP. Further, factor Xa does not require additional plasma components for its action because its inhibitory effects are detected in gel-filtered platelets. The effect of factor Xa was evident at physiological (1.3 mM) calcium concentrations. These results indicate that factor X. binding to platelets through factor Va not only stimulates thrombin formation but also has a countervailing effect by inhibiting TXA2 formation.

show abstract

The Inhibition of Activated Factor X with Di:isopropyl Fluorophosphate

Abstract: Summary. The esterase and coagulant activities of activated Factor X have been inhibited by radioactive di:isopropyl fluorophosphate. The amino acid sequence about the site of binding of the di:isopropyl moiety has been shown to be gly.asp.ser‐P‐gly.

Cited by 33 publications

References 17 publications

A Mechanism of Migration Inhibition Involving Components of the Coagulation System

A Mechanism of Migration Inhibition Involving Components of the Coagulation System

The Chemistry and Enzymology of Bovine Factor X

Inhibition of thromboxane A2 synthesis in human platelets by coagulation factor Xa.

Contact Info

Product

Resources

About