The binding of tranexamic acid to native (Glu) and modified (Lys) human plasminogen and its effect on conformation.

Sottrup‐Jensen

1995

Biochemical Journal

In the conversion of bovine plasminogen to bovine plasmin not only the expected urokinase-catalysed cleavage of Arg-557-Val-558, and the following autocatalytic cleavage separating the N-terminal peptide 1-77 from the heavy chain of plasmin, but also a cleavage at Arg-342-Met-343 between kringles 3 and 4 is seen. Here, kinetic studies of the interaction of bovine alpha 2-antiplasmin with bovine plasmin were performed on isolated bovine midiplasmin (lacking kringles 1-3) and on bovine plasmin containing all of the activation products from the bovine plasminogen. A series of experiments using stopped-flow fluorescence fast kinetics as well as conventional techniques suggests a reaction model in accordance with the one known for the human system. First, a tight complex (K1 in the nanomolar range) is formed in a fast reaction step; and second, a tightening of this complex occurs in a slow reaction step. The final complex is indeed so tight (Ki < or = pM), that the reaction for many practical purposes is legitimately considered irreversible. The stopped-flow method allows for the determination of reliable values of the second-order rate constant for the fast association step. At pH 7.4 and 25 degrees C, k+1 = 1.7 x 10(6) M-1 s-1 was obtained in the absence and k+1 = 0.9 x 10(6) M-1.s-1 in the presence of the kringles 1-3 domain of bovine plasmin. In contrast to this, substantial reductions of k+1 were seen in the presence of concentrations of 6-amino-hexanoic acid corresponding to lysine-binding-site interactions and far too low to be attributed to active-site interactions with the bovine plasmins (for each, Ki = 42 mM). All in all, the data indicated that the lysine-binding site(s) not of kringle 1, but of midiplasmin (those of kringles 4 and 5) are regulating the inhibition reaction.

Section: Discussionsupporting

confidence: 86%

Stopped-flow fluorescence kinetics of bovine α2-antiplasmin inhibition of bovine midiplasmin

Sottrup‐Jensen

1995

Biochemical Journal

“…Both ligands adopt a complementary binding mode to the LBS of K1. EACA and TXA interact with the LBS on K1 with K D values of 9.0 μM and 1.1 μM . Nonetheless, the remaining kringle domains except K3 can also be blocked by these lysine analogues, albeit with lower binding affinities .…”

Section: Ligands Of the Lysine Binding Sitementioning

confidence: 98%

“…Structures of lysine and its synthetic analogues 2 – 5 . EACA ( 2 ) and TXA ( 3b ) bind to the K1 domain with K D values of 9 μM and 1.1 μM, respectively.…”

Section: Ligands Of the Lysine Binding Sitementioning

confidence: 99%

“…EACA and TXA interact with the LBS on K1 with K D values of 9.0 μM 67 and 1.1 μM. 68 Nonetheless, the remaining kringle domains except K3 can also be blocked by these lysine analogues, albeit with lower binding affinities. 70 For both compounds, the affinities toward the kringle domains decrease in the order K1 > K4 > K5 > K2 ≫ K3.…”

Section: Ligands Of the Lysine Binding Sitementioning

confidence: 99%

See 1 more Smart Citation

Fibrinolysis Inhibitors: Potential Drugs for the Treatment and Prevention of Bleeding

et al. 2019

Hyperfibrinolytic situations can lead to lifethreatening bleeding, especially during cardiac surgery. The approved antifibrinolytic agents such as tranexamic acid, εaminocaproic acid, 4-aminomethylbenzoic acid, and aprotinin were developed in the 1960s without the structural insight of their respective targets. Crystal structures of the main antifibrinolytic targets, the lysine binding sites on plasminogen's kringle domains, and plasmin's serine protease domain greatly contributed to the structure-based drug design of novel inhibitor classes. Two series of ligands targeting the lysine binding sites have been recently described, which are more potent than the most-widely used antifibrinolytic agent, tranexamic acid. Furthermore, four types of promising active site inhibitors of plasmin have been developed: tranexamic acid conjugates targeting the S1 pocket and primed sites, substrate-analogue linear homopiperidylalanine-containing 4amidinobenzylamide derivatives, macrocyclic inhibitors addressing nonprimed binding regions, and bicyclic 14-mer SFTI-1 analogues blocking both, primed and nonprimed binding sites of plasmin. Furthermore, several allosteric plasmin inhibitors based on heparin mimetics have been developed.

“…These interactions between the N-terminal domain and intramolecular residues are critical for maintaining plasminogen in a tight closed conformation. The proteolytic cleavage at Lys77 by plasmin results in the removal of the N-terminal region, which results in the formation of a truncated form of plasminogen called Lys-plasminogen [65][66][67]. This form of plasminogen is in a more open conformation.…”

Section: Structure and Function Of Plasminogen And Plasminmentioning

confidence: 99%

Plasmin and Plasminogen System in the Tumor Microenvironment: Implications for Cancer Diagnosis, Prognosis, and Therapy

Bharadwaj

Holloway

Miller

et al. 2021

Cancers

The tumor microenvironment (TME) is now being widely accepted as the key contributor to a range of processes involved in cancer progression from tumor growth to metastasis and chemoresistance. The extracellular matrix (ECM) and the proteases that mediate the remodeling of the ECM form an integral part of the TME. Plasmin is a broad-spectrum, highly potent, serine protease whose activation from its precursor plasminogen is tightly regulated by the activators (uPA, uPAR, and tPA), the inhibitors (PAI-1, PAI-2), and plasminogen receptors. Collectively, this system is called the plasminogen activation system. The expression of the components of the plasminogen activation system by malignant cells and the surrounding stromal cells modulates the TME resulting in sustained cancer progression signals. In this review, we provide a detailed discussion of the roles of plasminogen activation system in tumor growth, invasion, metastasis, and chemoresistance with specific emphasis on their role in the TME. We particularly review the recent highlights of the plasminogen receptor S100A10 (p11), which is a pivotal component of the plasminogen activation system.