Function of streptokinase fragments in plasminogen activation

Shi, Guey‐Yueh; Chang, Bi-Ing; Chen, Shiau-May; Wu, Dung-Ho; Wu, Hua‐Lin

doi:10.1042/bj3040235

Cited by 55 publications

(90 citation statements)

References 33 publications

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“…SK complex and to bind a substrate Plg molecule, yet possesses a reduced catalytic rate constant for Plg activation (Lin et al, 1996). It appears therefore that whereas SK domain B mediates an interaction with Plg within the activator complex (this study; Shi et al, 1994;Young et al, 1995;Parrado et al, 1996), the function of inducing the active SK.Plg complex to proteolyse specifically the activation peptide bond of substrate Plg molecules appears to reside within domain C (Young et al, 1995).…”

Section: Discussionmentioning

confidence: 76%

“…However, this interaction alone is incapable of engendering Plg activation. The remaining Plg-binding determinants within SK have been proposed to reside within an N-terminal region (residues 1-90 approximately) (Shi et al, 1994;Rodriguez et al, 1995b;Young et al, 1995) contained within the N-terminal domain A (residues 1-145 approximately) (Conejero-Lara et al, 1996;Parrddo et al, 1996). Additionally, the presence of domain C (residues 290-380 approximately) appears to be essential for active site formation in the SK.Plg complex and subsequently for its Plg activator activity (Reed et al, 1995;Young et al, 1995;Parrado et al, 1996).…”

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confidence: 99%

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Analysis of the interactions between streptokinase domains and human plasminogen

et al. 1998

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The contrasting roles of streptokinase (SK) domains in binding human Glul-plasminogen (Plg) have been studied using a set of proteolytic fragments, each of which encompasses one or more of SK's three structural domains (A, B, C). Direct binding experiments have been performed using gel filtration chromatography and surface plasmon resonance. The latter technique has allowed estimation of association and dissociation rate constants for interactions between Plg and intact SK or SK fragments. Each of the SK fragments that contains domain B (fragments A2-B-C, A2-B, B-C, and B) binds Plg with similar affinity, at a level approximately 100-to 1,000-fold lower than intact SK. Experiments using 10 mM 6-aminohexanoic acid or 50 mM benzamidine demonstrate that either of these two lysine analogues abolishes interaction of domain B with Plg. Isolated domain C does not show detectable binding to Plg. Moreover, the additional presence of domain C within other SK fragments (B-C and A2-B-C) does not alter significantly their affinities for Plg. In addition, Plg-binding by a noncovalent complex of two SK fragments that contains domains A and B is similar to that of domain B. By contrast, species containing domain B and both domains A and C (intact SK and the two-chain complex AI . A2-B-C) show a significantly higher affinity for Plg, which could not be completely inhibited by saturating amounts of 6-AHA. These results show that SK domain B interacts with Plg in a lysine-dependent manner and that although domains A and C do not appear independently to possess affinity for Plg, they function cooperatively to establish the additional interactions with Plg to form an efficient native-like Plg activator complex.Keywords: fibrinolysis; lysine-binding site; plasminogen; serine protease; streptokinase; zymogen activation Streptococcus equisimilis streptokinase (SK) is a single-chain secreted protein of 414 amino acids (Malke et al., 1985), which indirectly causes the activation of the blood plasma zymogen human plasminogen (Plg) to the fibrinolytic enzyme plasmin (Christensen, 1945) via active-site formation within Plg. This proceeds without proteolytic cleavage by means of a rapid and avid binding

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Section: Discussionmentioning

confidence: 76%

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confidence: 99%

Analysis of the interactions between streptokinase domains and human plasminogen

et al. 1998

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“…Several previous studies have indicated the importance of approximately the first 60 residues at the N terminus of SK in the regulation of its Plg activator activity (Siefring & Castellino, 1976;Shi et al, 1994;Young et al, 1995;Parrado et al, 1996). These N-terminal peptides (similar to fragment AI) remain noncovalently bound to the rest of the SK chain in proteolytic preparations (Siefring & Castellino, 1976;Misselwitz et al, 1992;Parrado et al, 1996) and are capable of producing a large increase in the activity of other SK fragments (Shi et al, 1994;Parrado et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

“…These N-terminal peptides (similar to fragment AI) remain noncovalently bound to the rest of the SK chain in proteolytic preparations (Siefring & Castellino, 1976;Misselwitz et al, 1992;Parrado et al, 1996) and are capable of producing a large increase in the activity of other SK fragments (Shi et al, 1994;Parrado et al, 1996). Isolated fragment A1 has been described as being mainly unstructured at neutral pH, under conditions where it was capable of potentiating the activator activity of fragment A2-B-C up to 100-fold (Parrado et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

“…Several fragments and modified forms of SK have been isolated previously (Brockway & Castellino, 1974;Siefring & Castellino, 1976;Jackson et al, 1986;Malke et al, 1987;Misselwitz et al, 1992;Rodriguez et al, 1994Rodriguez et al, , 1995Shi et al, 1994;Reed et al, 1995;Young et al, 1995). A number of SK fragments remain folded when isolated in solution and a minority maintain an ability to cause Plg activation, although, in most cases, this occurs at substantially reduced rates when compared with native SK.…”

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Thermal stability of the three domains of streptokinase studied by circular dichroism and nuclear magnetic resonance

et al. 1996

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Streptococcus equisirnilis streptokinase (SK) is a single-chain protein of 414 residues that is used extensively in the clinical treatment of acute myocardial infarction due to its ability to activate human plasminogen (Plg). The mechanism by which this occurs is poorly understood due to the lack of structural details concerning both molecules and their complex. We reported recently (Parrado J et al ., 1996, Protein Sci 5693-704) that SK is composed of three structural domains (A, B, and C) with a C-terminal tail that is relatively unstructured. Here, we report thermal unfolding experiments, monitored by CD and NMR, using samples of intact SK, five isolated SK fragments, and two two-chain noncovalent complexes between complementary fragments of the protein. These experiments have allowed the unfolding processes of specific domains of the protein to be monitored and their relative stabilities and interdomain interactions to be characterized. Results demonstrate that SK can exist in a number of partially unfolded states, in which individual domains of the protein behave as single cooperative units. Domain B unfolds cooperatively in the first thermal transition at approximately 46°C and its stability is largely independent of the presence of the other domains. The hightemperatwe transition in intact SK (at approximately 63 "C) corresponds to the unfolding of both domains A and C. Thermal stability of domain C is significantly increased by its isolation from the rest of the chain. By contrast, cleavage of the Phe 63-Ala 64 peptide bond within domain A causes thermal destabilization of this domain. The two resulting domain portions (AI and A2) adopt unstructured conformations when separated. AI binds with high affinity to all fragments that contain the A2 portion, with a concomitant restoration of the native-like fold of domain A. This result demonstrates that the mechanism whereby A1 stimulates the plasminogen activator activities of complementary SK fragments is the reconstitution of the native-like structure of domain A.

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Streptokinase

Fay

2002

Wiley Encyclopedia of Molecular Medicine

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Function of streptokinase fragments in plasminogen activation

Cited by 55 publications

References 33 publications

Analysis of the interactions between streptokinase domains and human plasminogen

Analysis of the interactions between streptokinase domains and human plasminogen

Thermal stability of the three domains of streptokinase studied by circular dichroism and nuclear magnetic resonance

Streptokinase

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