Direct evidence for the generation of an active site in the plasminogen moiety of the streptokinase-human plasminogen activator complex

Schick, Lloyd A.

doi:10.1016/s0006-291x(74)80355-4

Cited by 84 publications

(42 citation statements)

References 9 publications

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“…The thrombolytic drug and streptococcal pathogenicity factor, streptokinase (SK) activates Pg to Pm through a unique mechanism (1,2). SK acts by binding Pg and Pm in stoichiometric SK⅐Pg* and SK⅐Pm catalytic complexes that bind Pg as a specific substrate and proteolytically convert it into Pm by cleavage of Arg 561 -Val 562 (1)(2)(3)(4)(5)(6)(7)(8). The active site of Pg is conformationally induced in the catalytic SK⅐Pg* complex through the molecular sexuality mechanism, without the typically required proteolytic cleavage (3, 5, 6, 9 -11).…”

mentioning

confidence: 99%

Rapid-reaction Kinetic Characterization of the Pathway of Streptokinase-Plasmin Catalytic Complex Formation

Verhamme

Bock

2008

Journal of Biological Chemistry

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confidence: 99%

Rapid-reaction Kinetic Characterization of the Pathway of Streptokinase-Plasmin Catalytic Complex Formation

Verhamme

Bock

2008

Journal of Biological Chemistry

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“…SK possesses no intrinsic catalytic activity but interacts with Pg and Pm, converting both the zymogen and active proteinase into specific proteolytic Pg activators (14 -19). SK binding to Pg results in conformational expression of an active catalytic site on the zymogen without the usual strict requirement for peptide bond cleavage (14,16,17). Pm is generated subsequently by proteolytic cleavage of Arg 561 -Val 562 , and the SK⅐Pm complex propagates Pg activation through expression of a substrate recognition exosite (20,21).…”

mentioning

confidence: 99%

“…Early studies (14,16,17) demonstrated that interaction of SK with Pg produced the activated Pg catalytic site in the SK⅐Pg* complex. Subsequent kinetic studies indicated that Pg activation involved an initially formed SK⅐Pg* activation complex and an isomerized form of the complex (22,23).…”

mentioning

confidence: 99%

Resolution of Conformational Activation in the Kinetic Mechanism of Plasminogen Activation by Streptokinase

Boxrud¹,

Verhamme

Bock

2004

Journal of Biological Chemistry

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Streptokinase (SK) 1 is used clinically as a thrombolytic drug to activate plasminogen (Pg) to plasmin (Pm), the serine proteinase responsible for dissolution of fibrin clots (1). Native [Glu]Pg is a multidomain zymogen consisting of a 77-residue N-terminal peptide, five kringle domains, and a serine proteinase catalytic domain that is activated by cleavage of Arg 561 -Val 562 (2, 3).[Glu]Pg is in a compact conformation, maintained by intramolecular interactions between the N-terminal peptide and lysine-binding sites in kringles 4 and 5 (4 -6). Release of the N-terminal peptide by Pm cleavage generates [Lys]Pg, which adopts an extended conformation and is cleaved by plasminogen activators at a faster rate (5, 7-13). SK possesses no intrinsic catalytic activity but interacts with Pg and Pm, converting both the zymogen and active proteinase into specific proteolytic Pg activators (14 -19). SK binding to Pg results in conformational expression of an active catalytic site on the zymogen without the usual strict requirement for peptide bond cleavage (14,16,17). Pm is generated subsequently by proteolytic cleavage of Arg 561 -Val 562 , and the SK⅐Pm complex propagates Pg activation through expression of a substrate recognition exosite (20,21).It is well established that both conformational and proteolytic activation contribute to SK-induced Pg activation, but there are a number of unresolved questions concerning the mechanism of conformational activation and its coupling to subsequent proteolytic Pm formation. Early studies (14,16,17) demonstrated that interaction of SK with Pg produced the activated Pg catalytic site in the SK⅐Pg* complex. Subsequent kinetic studies indicated that Pg activation involved an initially formed SK⅐Pg* activation complex and an isomerized form of the complex (22, 23). The isomerization was time-, chloride ion-, and fibrinogen-dependent, and the active complexes interconverted slowly under certain experimental conditions. In other studies, a species of Pg isolated from a mixture of SK and Pg was reported to be an active "virgin enzyme" form of free Pg*, suggesting irreversible conformational activation (24). The relationship between SK-Pg binding and conformational activation and its reversibility have not been clearly established.Previous studies of the mechanism of Pg activation by SK have not taken into account the binding affinities of SK for Pg and Pm species, primarily because consistent and reliable equilibrium binding constants have not been available. A number of studies have examined the binding interactions by various experimental approaches but have resulted in a very broad range of dissociation constants, varying from 28 pM to 220 nM for [Glu]Pg (25-32), for example, where the higher affinities may result from Pm generation in SK/Pg mixtures. Our equilibrium binding studies have employed active site-labeled fluorescent Pg and Pm analogs to quantitate SK binding in the absence of proteolytic reactions (21,28,33,34). The results for the active site-labeled proteins support a rela...

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“…The SK and human plasminogen (HPlg) complex can activate Plg to plasmin (Plm) from different mammalian species (3)(4)(5)(6)(7)(8)(9)(10). Plm thus produced in the blood circulation in turn catalyzes the hydrolysis of fibrin and dissolution of blood clots.…”

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confidence: 99%

Plasminogen Activation by Streptokinase via a Unique Mechanism

Young¹,

Shi²,

Wu³

et al. 1998

Journal of Biological Chemistry

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Direct evidence for the generation of an active site in the plasminogen moiety of the streptokinase-human plasminogen activator complex

Cited by 84 publications

References 9 publications

Rapid-reaction Kinetic Characterization of the Pathway of Streptokinase-Plasmin Catalytic Complex Formation

Rapid-reaction Kinetic Characterization of the Pathway of Streptokinase-Plasmin Catalytic Complex Formation

Resolution of Conformational Activation in the Kinetic Mechanism of Plasminogen Activation by Streptokinase

Plasminogen Activation by Streptokinase via a Unique Mechanism

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