Reaction of human α<sub>2</sub>‐antiplasmin and plasmin Stopped‐flow fluorescence kinetics

Christensen, Ulla; Bangert, Kristian; Thorsen, Sixtus

doi:10.1016/0014-5793(96)00429-2

Cited by 37 publications

(26 citation statements)

References 52 publications

(63 reference statements)

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“…The role of fibrin in slowing the rate of Pn inhibition by AP has been extensively studied with lysine analogues (2)(3)(4)23) and soluble (5,6) or immobilized (15) fibrin derivatives. In every case, occupation of the kringle domain of Pn slowed inhibition by 10 -398-fold depending on the system used to study the reaction.…”

Section: Discussionmentioning

confidence: 99%

Activated Thrombin-activatable Fibrinolysis Inhibitor Reduces the Ability of High Molecular Weight Fibrin Degradation Products to Protect Plasmin from Antiplasmin

Schneider

Brufatto²,

Neill³

et al. 2004

Journal of Biological Chemistry

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Activated thrombin-activable fibrinolysis inhibitor (TAFIa) is a carboxypeptidase B-like plasma enzyme that can slow clot lysis by removing lysine residues exposed on fibrin as it is cleaved by plasmin. Previously, it was shown that fibrin treated with TAFIa is less able to promote plasminogen activation by tissue-type plasminogen activator. In this study, the effect of TAFIa modification of a fibrin surface on the rate of plasmin inhibition by antiplasmin was studied using high molecular weight fibrin degradation products (HMw-FDPs) as a soluble model for intact plasmin-modified fibrin. To quantify the inhibition, a novel end point assay was employed where plasmin, antiplasmin, and cofactors were mixed in the presence of a chromogenic substrate and the end point in the substrate hydrolysis reaction was used to measure the second order rate constant of inhibition. When HMw-FDPs were titrated in the presence of plasmin and antiplasmin, the rate constant for inhibition decreased by 16-fold at saturation (9.6 ؋ 10

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Section: Discussionmentioning

confidence: 99%

Activated Thrombin-activatable Fibrinolysis Inhibitor Reduces the Ability of High Molecular Weight Fibrin Degradation Products to Protect Plasmin from Antiplasmin

Schneider

Brufatto²,

Neill³

et al. 2004

Journal of Biological Chemistry

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“…Effect of DNA on Interaction of PL with ␣ 2 AP-The effects of DNA on the fast step of the reaction between PL and ␣ 2 AP were determined observing the change in the intrinsic tryptophan fluorescence resulting from the Michaelis complex formation (63). Briefly, equimolar amounts of PL and ␣ 2 AP were mixed in an SX-20 thermostabilized at 25°C; the change in fluorescence emission with time (excitation at 290 nm) was monitored through a 335-nm cutoff filter.…”

Section: Methodsmentioning

confidence: 99%

“…Briefly, equimolar amounts of PL and ␣ 2 AP were mixed in an SX-20 thermostabilized at 25°C; the change in fluorescence emission with time (excitation at 290 nm) was monitored through a 335-nm cutoff filter. The second-order rate constant (k 2 ) was calculated as described elsewhere (63).…”

Section: Methodsmentioning

confidence: 99%

“…Finally, the effect of dsDNA (0 -10 g/ml) and oligo(dAT) 33 (0 -10 M) on the rate constant for the second slow step of the reaction (k ϩ2 ; Scheme 2) was studied by monitoring the residual PL amidolytic activity after mixing high concentrations of PL (0.1-0.5 M) with equimolar amounts of ␣ 2 AP in the presence of the fluorogenic substrate, as described previously (63,77). Although the values of k ϩ2 did not change with an increase in the dsDNA concentration and slightly decreased with an increase in the [oligo(dAT) 33 ] (Fig.…”

Section: Tablementioning

confidence: 99%

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Effects of Extracellular DNA on Plasminogen Activation and Fibrinolysis

Komissarov¹,

Florova²,

Idell³

2011

Journal of Biological Chemistry

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Background: Elevated levels of extracellular DNA and aberrant fibrinolysis occur in a range of severe diseases. Results: DNA competes with fibrin for fibrinolytic enzymes. DNA stimulates fibrin-independent plasminogen activation and increases enzyme susceptibility to serpins. Conclusion: DNA is a macromolecular template that both potentiates and inhibits fibrinolysis. Significance: Understanding the interaction of DNA with the fibrinolytic system could improve the outcomes of fibrinolytic therapy.

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“…22 Earlier studies showed that kringle 4 is important in the interaction of plasmin with a2AP, but that kringles 1, 2, 3, and 5 are also involved. 23,24 In the second step, which is an irreversible first-order reaction, the arginine residue in position 376 of a2AP (numbering in this manuscript is according to methionine in position 1) in the reactive center loop (RCL) forms a covalent bond with the active site serine of plasmin. 14,20 This results in the PAP complex, accompanied by complete loss of plasmin activity and cleavage of a scissile peptide bond of a2AP.…”

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confidence: 99%

Natural heterogeneity of α2-antiplasmin: functional and clinical consequences

Abdul

Leebeek

Rijken

et al. 2016

Blood

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Human a2-antiplasmin (a2AP, also called a2-plasmin inhibitor) is the main physiological inhibitor of the fibrinolytic enzyme plasmin. a2AP inhibits plasmin on the fibrin clot or in the circulation by forming plasmin-antiplasmin complexes. Severely reduced a2AP levels in hereditary a2AP deficiency may lead to bleeding symptoms, whereas increased a2AP levels have been associated with increased thrombotic risk. a2AP is a very heterogeneous protein. In the circulation, a2AP undergoes both amino terminal (N-terminal) and carboxyl terminal (C-terminal) proteolytic modifications that significantly modify its activities. About 70% of a2AP is cleaved at the N terminus by antiplasmin-cleaving enzyme (or soluble fibroblast activation protein), resulting in a 12-amino-acid residue shorter form. The glutamine residue that serves as a substrate for activated factor XIII becomes more efficient after removal of the N terminus, leading to faster crosslinking of a2AP to fibrin and consequently prolonged clot lysis. In approximately 35% of circulating a2AP, the C terminus is absent. This C terminus contains the binding site for plasmin(ogen), the key component necessary for the rapid and efficient inhibitory mechanism of a2AP. Without its C terminus, a2AP can no longer bind to the lysine binding sites of plasmin(ogen) and is only a kinetically slow plasmin inhibitor. Thus, proteolytic modifications of the N and C termini of a2AP constitute major regulatory mechanisms for the inhibitory function of the protein and may therefore have clinical consequences. This review presents recent findings regarding the main aspects of the natural heterogeneity of a2AP with particular focus on the functional and possible clinical implications. (Blood. 2016; 127(5):538-545) Introduction a2-antiplasmin (a2AP, also called a2-plasmin inhibitor) is a key player in the fibrinolytic system (Figure 1). The fibrinolytic system is crucial for dissolving fibrin clots, facilitating tissue repair, and preventing clots from occluding vessels.1 Recent clinical studies have shown that reduced fibrinolysis (eg, due to an increase in a2AP level) is associated with an increase in both venous and arterial thrombotic risk. 2In contrast, an increase in fibrinolysis due to a2AP deficiency is associated with hemophilia-like bleeding symptoms, which typically occur after initial hemostasis as a result of the premature dissolution of fibrin. The phenotype of a2AP deficiency is heterogeneous. Complete congenital a2AP deficiency leads to severe bleeding with hemophilialike bleeding symptoms such as joint bleeding, whereas heterozygous a2AP-deficient patients typically have mild or no bleeding symptoms. 3,4 In addition, acquired a2AP deficiency may also occur in liver disease 5 and amyloidosis 6 or during fibrinolytic therapy. 7The main enzyme of the fibrinolytic system is the serine protease plasmin, which is predominantly responsible for the degradation of fibrin into rapidly cleared soluble fibrin degradation products (Figure 1). The inactive proenzyme plasminogen ca...

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Reaction of human α₂‐antiplasmin and plasmin Stopped‐flow fluorescence kinetics

Cited by 37 publications

References 52 publications

Activated Thrombin-activatable Fibrinolysis Inhibitor Reduces the Ability of High Molecular Weight Fibrin Degradation Products to Protect Plasmin from Antiplasmin

Activated Thrombin-activatable Fibrinolysis Inhibitor Reduces the Ability of High Molecular Weight Fibrin Degradation Products to Protect Plasmin from Antiplasmin

Effects of Extracellular DNA on Plasminogen Activation and Fibrinolysis

Natural heterogeneity of α2-antiplasmin: functional and clinical consequences

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Reaction of human α2‐antiplasmin and plasmin Stopped‐flow fluorescence kinetics

Cited by 37 publications

References 52 publications

Activated Thrombin-activatable Fibrinolysis Inhibitor Reduces the Ability of High Molecular Weight Fibrin Degradation Products to Protect Plasmin from Antiplasmin

Activated Thrombin-activatable Fibrinolysis Inhibitor Reduces the Ability of High Molecular Weight Fibrin Degradation Products to Protect Plasmin from Antiplasmin

Effects of Extracellular DNA on Plasminogen Activation and Fibrinolysis

Natural heterogeneity of α2-antiplasmin: functional and clinical consequences

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Product

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Reaction of human α₂‐antiplasmin and plasmin Stopped‐flow fluorescence kinetics