title: Enhanced activator activity of the mixture of streptokinase and a modified form of plasminogen (Lys-plasminogen) in the presence of fibrin: role of conformational change of plasminogen.
abstract: Equimolar concentrations of Lys-plasminogen (Lys-PLG) and streptokinase (SK) were mixed with various concentrations of fibrin, fibrinogen, fragment D or E (potentiating agents). The activity of the mixture was measured by the hydrolysis of S-2251. Kinetic analyses indicated that catalytic rate constant (kcat) of the hydrolysis of S-2251 increased in the presence of increasing amounts of potentiating agents. Km did not change in their presence. Effectiveness of the enhancement of the hydrolysis of S-2251 was in the order of fibrin greater than fibrinogen greater than E greater than D. It could be concluded that a complex of SK, Lys-PLG and potentiating agent is a better enzyme, thus activator, than a complex of SK and Lys-PLG. Since Lys-PLG does not change its conformation and its activation rate upon interaction with fibrin, the enhanced activator activity of complex of SK, Lys-PLG and potentiating agent may not be due to the conformational change of Lys-PLG.
authors.affiliation: Department of Physiology, Hamamatsu University, School of Medicine, Shizuoka, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Takada
authors.forename: Y
authors.initials: Y
authors.lastname: Takada
authors.forename: Y
authors.initials: Y
authors.lastname: Sugawara
mesh_terms: D002863:Chromogenic Compounds / Q000378:metabolism; D004357:Drug Synergism; D005337:Fibrin / Q000494:pharmacology*; D005338:Fibrin Fibrinogen Degradation Products / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D009842:Oligopeptides / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D010958:Plasminogen / Q000494:pharmacology*; D010960:Plasminogen Activators / Q000494:pharmacology*; D011487:Protein Conformation; D013053:Spectrophotometry; D013300:Streptokinase / Q000494:pharmacology*; D013917:Thrombin / Q000494:pharmacology
chemical_list: D002863:Chromogenic Compounds; D005338:Fibrin Fibrinogen Degradation Products; D009842:Oligopeptides; D010446:Peptide Fragments; C015214:fibrinogen D fragment; C018543:fibrinogen fragment E; C018998:lysyl-plasminogen; C018788:valyl-leucyl-lysine 4-nitroanilide; D005337:Fibrin; D010958:Plasminogen; D013300:Streptokinase; D010960:Plasminogen Activators; D013917:Thrombin