Enhanced Affinity of Fibrinogen and Factor XIII Induced by Limited Proteolysis

1979 ◽  
Author(s):  
S.I. Chung ◽  
J.E. Folk ◽  
J.S. Finlayson

Previous studies have shown that tissue transglutaminase has strong affinity for fibrinogen. In this study, the binding of protransglutaminase, i.e., plasma Factor XIII(a2b2) and platelet Factor XIII (a2), to fibrinogen was examined by ultracentrifugation, exclusion and affinity chromatography, Immunoelectrophoresis, and salt precipitation. Affinity was detected only by salting out and affinity chromatography. Limited proteolysis to form Factor XIIIa (a′2b2 and a′2) enhanced the affinity for fibrinogen. Limited proteolysis of fibrinogen by thrombin or ancrod enhanced affinity for both a2b2 and a2. Fibrin also bound a′2b2 and a′2. The b2 subunit exhibited no affinity for fibrinogen or fibrin. Thus, in the presence of fibrin(ogen), a′2b2 gave rise to a fibrin(ogen)-a′2 complex, and the b2 subunit was liberated.The enhanced affinity for fibrinogen induced by limited proteolysis of Factor XIII suggests that fibrinogen could serve to adsorb active transglutaminase(s) released or generated in the circulation.

Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1028-1034 ◽  
Author(s):  
CS Greenberg ◽  
JV Dobson ◽  
CC Miraglia

Abstract The binding of plasma factor XIII to fibrinogen or fibrin that has been chemically or enzymatically induced to polymerize was studied. Factor XIII binding was assayed using a 3H-putrescine incorporation assay and an 125I-plasma factor XIII binding assay. More than 80% of the native and radiolabeled plasma factor XIII was bound to fibrin I formed by reptilase in EDTA, citrate, or heparin anticoagulated plasma. Plasma factor XIII and 125I-factor XIII was bound (89.6% to 92.5%) to fibrin II formed by thrombin in either citrate or EDTA anticoagulated plasma. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of 125I-plasma factor XIII bound to fibrin I or fibrin II formed by reptilase or thrombin in the presence of EDTA demonstrated the b2- subunit remained bound to the a-chains or thrombin-cleaved a-chains. In the presence of calcium chloride and thrombin, the b2-subunit dissociated and factor XIIIa was bound. Protamine sulfate caused fibrinogen polymerization in the absence of divalent cations and reduced both plasma factor XIII and immunologic fibrinogen levels. Fibrinogen polymerized by protamine sulfate bound plasma factor XIII and the a2-subunit of 125I-platelet factor XIII. Plasma factor XIII was also bound to sonicated non-cross-linked fibrin II in either normal plasma or afibrinogenemic plasma. Plasma levels of several coagulation proteins were unchanged after the addition of reptilase, protamine sulfate, or sonicated fibrin to plasma. These results demonstrate that a specific binding site for the a2-subunit of plasma factor XIII is present on polymerized fibrinogen, fibrin I, and fibrin II. Furthermore, the presence of divalent cations, thrombin-cleavage of plasma factor XIII, and release of fibrinopeptides A or B are not required for plasma factor XIII binding to polymerized fibrinogen and fibrin.


1997 ◽  
Vol 324 (3) ◽  
pp. 797-805 ◽  
Author(s):  
Sarah FINNEY ◽  
Lisa SEALE ◽  
Roy T. SAWYER ◽  
Robert B. WALLIS

1. Crude salivary gland extract of the giant Amazon leech, Haementeria ghilianii, contains an inhibitor of plasma factor XIIIa. 2. The inhibitory agent was purified to homogeneity by anion-exchange, cation-exchange, gel-filtration and reverse-phase chromatography to yield a single band on SDS/PAGE with an apparent molecular mass of 7.3 kDa. It has been named tridegin. 3. Micro-sequencing of proteolytic fragments showed tridegin to be a peptide of 66 amino acids. The sequence is unique with little similarity to other leech-derived proteins. 4. Inhibition of plasma factor XIIIa activity was confirmed by four independent methods: tridegin increased the solubility of fibrin clots in urea, inhibited ammonia produced from the incorporation of ethylamine into casein, inhibited the incorporation of 5′-(biotinamido)pentylamine into casein and prevented γ-dimer formation in clotting fibrinogen. 5. The IC50 of tridegin (approx. 9.2 nM) is very close to the concentration of factor XIIIa used in the assay and in fact depends on its concentration. This is the most potent inhibitor of factor XIIIa yet described. 6. Tridegin also inhibits platelet factor XIIIa (factor XIIIAa) with a similar potency to that of the plasma enzyme. 7. Tridegin also inhibits tissue transglutaminase but with lower potency and independently of the enzyme concentration. 8. Tridegin appears to be specific for transglutaminases, since it has no effect on the coagulation times of human plasma, on thrombin or factor Xa. Moreover it has no effect on other thiol-containing enzymes and has no ability to digest fibrinogen or cleave the isopeptide substrate, l-γ-glutamyl-4-nitroanilide.


1988 ◽  
Vol 256 (3) ◽  
pp. 1013-1019 ◽  
Author(s):  
C S Greenberg ◽  
J J Enghild ◽  
A Mary ◽  
J V Dobson ◽  
K E Achyuthan

Purified platelet Factor XIII was radioiodinated and then partially degraded by thrombin or trypsin, and a fibrin-binding fragment was identified by autoradiography and immunoblotting following separation by SDS/polyacrylamide-gel electrophoresis. Limited proteolysis of 125I-Factor XIII by thrombin or trypsin produced an 125I-51 kDa fragment and an unlabelled 19 kDa fragment. The 51 kDa fragment was purified by h.p.l.c. on a TSK-125 gel-filtration column. Partial amino acid sequence analysis of the 51 kDa fragment indicated that it was similar in sequence to the Gly38-Lys513 segment in placental Factor XIII a-chain. More than 70% of the 51 kDa fragment bound to fibrin, whereas the 19 kDa fragment did not bind. The active site was localized to the 51 kDa fragment since this fragment expressed transglutaminase activity, cross-linked fibrin and fibrinogen and incorporated iodo[14C]acetamide into the active-site cysteine residue. Isolation of a fibrin-binding fragment expressing transglutaminase activity demonstrates that each a-chain of the dimeric Factor XIIIa could function independently to cross-link fibrin. The fibrin-binding site could play an important role in localizing Factor XIIIa to the fibrin clot.


Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1028-1034 ◽  
Author(s):  
CS Greenberg ◽  
JV Dobson ◽  
CC Miraglia

The binding of plasma factor XIII to fibrinogen or fibrin that has been chemically or enzymatically induced to polymerize was studied. Factor XIII binding was assayed using a 3H-putrescine incorporation assay and an 125I-plasma factor XIII binding assay. More than 80% of the native and radiolabeled plasma factor XIII was bound to fibrin I formed by reptilase in EDTA, citrate, or heparin anticoagulated plasma. Plasma factor XIII and 125I-factor XIII was bound (89.6% to 92.5%) to fibrin II formed by thrombin in either citrate or EDTA anticoagulated plasma. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of 125I-plasma factor XIII bound to fibrin I or fibrin II formed by reptilase or thrombin in the presence of EDTA demonstrated the b2- subunit remained bound to the a-chains or thrombin-cleaved a-chains. In the presence of calcium chloride and thrombin, the b2-subunit dissociated and factor XIIIa was bound. Protamine sulfate caused fibrinogen polymerization in the absence of divalent cations and reduced both plasma factor XIII and immunologic fibrinogen levels. Fibrinogen polymerized by protamine sulfate bound plasma factor XIII and the a2-subunit of 125I-platelet factor XIII. Plasma factor XIII was also bound to sonicated non-cross-linked fibrin II in either normal plasma or afibrinogenemic plasma. Plasma levels of several coagulation proteins were unchanged after the addition of reptilase, protamine sulfate, or sonicated fibrin to plasma. These results demonstrate that a specific binding site for the a2-subunit of plasma factor XIII is present on polymerized fibrinogen, fibrin I, and fibrin II. Furthermore, the presence of divalent cations, thrombin-cleavage of plasma factor XIII, and release of fibrinopeptides A or B are not required for plasma factor XIII binding to polymerized fibrinogen and fibrin.


1975 ◽  
Author(s):  
Jan McDonagh ◽  
Richard P. McDonagh

A new method for studying the interactions of plasma factor XIII subunits, as well as purifying both plasma and platelet factor XIII, has been developed using an organomer-curial linked to agarose. Native plasma factor XIII a subunit binds to the ligand accompanied by b subunit, which can be dissociated from the ligated a subunit by treatment with thrombin and calcium. With various combinations of thrombin, calcium, and alteration of ionic strength it has been shown that: (a) both unactivated a subunit and thrombin activated a’ subunit bind to the ligand; (b) “excess” b subunit present in highly purified preparations of plasma factor XIII dissociates and can be eluted at low ionic strength in the absence of calcium or thrombin; (c) in our preparations of highly purified plasma factor XIII approximately 40% of b subunit is in “excess”; (d) the remaining b subunit can be eluted with thrombin and calcium; (e) both a and a’ subunits can be eluted with dithiothreitol ; (f ) when plasma factor XIII zymogen is applied to the column approximately equal amounts of a and b subunits co-elute with dithiothreitol. These observations offer further evidence for the roles of thrombin and calcium in the activation of plasma factor XIII and provide a new tool for studying the structure-function relationships of factor XIII.Supported by Grants HL 14228 and HL 06350 from the National Institutes of Health, U.S.A.


1976 ◽  
Vol 36 (03) ◽  
pp. 542-550 ◽  
Author(s):  
Mircea P. Cucuianu ◽  
K Miloszewski ◽  
D Porutiu ◽  
M. S Losowsky

SummaryPlasma factor XIII activity measured by a quantitative assay was found to be significantly higher in hypertriglyceridaemic patients (type IV and combined hyperlipoproteinaemia), as compared to normolipaemic controls. No such elevation in plasma factor XIII activity was found in patients with type IIa hyperlipaemia. Plasma pseudocholinesterase was found to parallel the elevated factor XIII activity in hypertriglyceridaemic subjects.In contrast, platelet factor XIII activity was not raised in hyperlipaemic subjects, and plasma factor XIII was found to be normal in a normolipaemic subject with throm-bocythaemia.It was concluded that there is no significant contribution from platelets to plasma factor XIII activity, and that the observed increase in plasma factor XII in hypertriglyceridaemia results from enhanced hepatic synthesis of the enzyme.


1974 ◽  
Vol 141 (3) ◽  
pp. 683-691 ◽  
Author(s):  
Rodney D. Cooke

1. The Ca2+dependence of the activity of plasma Factor XIIIa was studied by using the continuous assay based on the incorporation of dansylcadaverine into dephosphorylated acetylated β-casein (β-substrate). The Km for Ca2+is about 0.170mm. 2. At low concentrations of Ca2+there was a lag in attaining the steady-state rate. The size of the lag was decreased and eventually abolished if the enzyme was preincubated with a high concentration of Ca2+before assay. The concentration of Ca2+required to decrease the lag phase by 50% in 10min depended on the protein concentration: at 0.87mg of protein/ml it required 17mm-Ca2+and at 0.44mg/ml it needed 10mm-Ca2+. 3. The concentrations of Ca2+required either to abolish the lag phase in the appearance of enzyme activity or to activate the essential thiol for reaction with 5,5′-dithiobis-(2-nitrobenzoate) in 10min incubation were similar at the same protein concentration. This indicated that Ca2+induces a conformation change that is responsible for both phenomena. A model is proposed that links this conformation change to the dissociation of the tetrameric enzyme. 4. This was supported by the observation that the addition of excess of b chains to the Factor XIIIa (a′2b2) increased the concentration of Ca2+required to expose the reactive thiol, and inhibited the Ca2+-dependent aggregation of a′ chains. 5. Platelet Factor XIIIa (a′2) was inhibited by 5,5′-dithiobis-(2-nitrobenzoate) in the absence of Ca2+, and no lag phases were observed in attaining the steady-state rate at low Ca2+concentrations, thus confirming the model for the activation of the plasma enzyme. 6. The Ca2+dependence of platelet Factor XIIIa indicated that Ca2+has an additional role in the enzyme mechanism of the plasma enzyme, perhaps being involved in substrate binding. 7. The dependence of the stability of plasma Factor XIIIa on Ca2+and protein concentration indicates that the decay in activity is related to the tetramer dissociation. 8. β-Substrate decreased the Ca2+concentration required for (1) abolition of the lag phase and (2) enzyme inhibition by thiol reagents. The effect on the former is greater than on the latter. 9. The role of the b chains of the plasma Factor and the evolutionary significance of the plasma and platelet Factors are considered.


Blood ◽  
1978 ◽  
Vol 52 (3) ◽  
pp. 581-591 ◽  
Author(s):  
JC Nelson ◽  
RG Lerner

Abstract Factor XIIIa (active fibrin-stabilizing factor) generated in heat- defibrinated plasma by the addition of thrombin can be measured by 14C- putrescine incorporation into casein. Modification of this assay be substituting 3H-putrescine of high specific activity as the donor amine permits measurement of amine incorporation by plasma even in the absence of added thrombin. Incorporation is calcium dependent, inhibited by iodoacetamide, and absent from congenital factor XIII- deficient plasma and from normal platelets. The transamidating activity detected by radioenzymatic assay catalyzed the formation of gamma-gamma dimers and alpha polymers of fibrin and was thus biologically functional. This fibrin cross-linking activity was absent from factor XIII-deficient plasma. These experiments show (1) some factor XIII is present in plasma as factor XIIIa; (2) this factor XIIIa can cross-link fibrin and thus has biologic activity as well; and (3) this activity is not present in factor XIII-deficient plasma. Factor XIIIa in normal plasma is possibly activated in vivo, perhaps by circulating thrombin, factor Xa, or other proteolytic enzymes.


1987 ◽  
Author(s):  
C W Francis ◽  
V J Marder

Following fibrin polymerization, activated factor XIII stabilizes the clot by catalyzing the formation of specific intermolecular covalent crosslinks between pairs of y chains to form dimers and also among two or more a chains to form polymers. We have identified a series of previously uncharacterized a chain polymers with a wide range of sizes, including some with apparent Mr in excess of several million. Additionally, we establish the role of high concentrations of factor XIII in the extent and rate of α-polymer formation and provide evidence that the factor XIII required can be provided by platelets. Using SDS gel electrophoresis, we find that fibrin prepared from purified fibrinogen or from platelet-deficient plasma contains a series of 21 factor XIIIa crosslinked a chain polymers with Mr from 140,000 to 770,000. The mean Mr difference between individual polymers of 32,000 is consistent with a staggered, overlapping sequential addition of monomers to the growing α-polymer chain. In plasma containing no platelets, α-polymer formation was incomplete with residual α-monomer remaining. Progressively higher platelet counts facilitated more rapid crosslinking of a chains into larger polymers. Intact platelets were not required to promote crosslinking, since platelets lysed by freezing and thawing were also effective. Enrichment of plasma with placental factor XIII in an amount equal to that contained in platelets was as effective as platelets in accelerating the rate of formation and increasing the size of α-chain polymers. We conclude that platelets are a principal source of factor XIII for maximal fibrin stabilization, providing a larger quantity than is available from plasma alone and regulating both the rate and extent of α-polymer formation in thrombi or hemostatic plugs at sites of vascular injury.


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