title: Interaction of a plasminogen activator proteinase, LV-PA with human alpha2-macroglobulin.
abstract: Lachesis venom plasminogen activator (LV-PA) is a 33-kDa serine proteinase isolated from bushmaster (Lachesis muta muta) snake venom, which activates the fibrinolytic system in vitro. This study has examined the effect of the plasma proteinase inhibitor alpha2-macroglobulin (alpha2-M) towards LV-PA and compares it with the effect on tissue type plasminogen activator (t-PA). The proteolytic activity of LV-PA alone or previously incubated with human plasminogen (Plg) on the large molecular mass protein substrates, dimethylcasein (DMC) and fibrinogen (Fg) was completely inhibited by human alpha2-M. However, the synthetic peptides Tos-Gly-Pro-Lys-pNA and H-D-Pro-Phe-Arg-pNA (S-2302) were hydrolyzed with almost no reduction in rate. At pH 7.4 and 37 degrees C the proteinase (0.15 microM over 15 min) interacted with alpha2-M, and each mole of alpha2-M bound 2 mol of enzyme. Sodium dodecyl sulfate gel electrophoresis of reduced samples showed that the interaction of alpha2-M with either LV-PA or t-PA preincubated with Plg resulted in the formation of approximately 90 kDa fragments and high molecular mass complexes (Mr 180 kDa), generated by the incubation mixture (LV-PA or t-PA) and Plg. The data suggest that LV-PA is a direct-type PA and its fibrinolytic effect can be reduced by alpha2-M in vivo.
authors.affiliation: Research and Development Center, Ezequiel Dias Fundation, 30510-010 Belo Horizonte, MG, Brazil.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Hermogenes
authors.forename: Michael
authors.initials: M
authors.lastname: Richardson
authors.forename: Arinos
authors.initials: A
authors.lastname: Magalhaes
authors.forename: Armando
authors.initials: A
authors.lastname: Yarleque
authors.forename: Edith
authors.initials: E
authors.lastname: Rodriguez
authors.forename: Eladio F
authors.initials: EF
authors.lastname: Sanchez
mesh_terms: D003435:Crotalid Venoms / Q000201:enzymology / Q000494:pharmacology*; D004347:Drug Interactions; D006801:Humans; D010960:Plasminogen Activators / Q000302:isolation & purification / Q000494:pharmacology*; D012697:Serine Endopeptidases / Q000187:drug effects* / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000494:pharmacology*; D000979:alpha-2-Antiplasmin / Q000494:pharmacology; D000511:alpha-Macroglobulins / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D003435:Crotalid Venoms; C072644:Lachesis venom; D000979:alpha-2-Antiplasmin; D000511:alpha-Macroglobulins; D010960:Plasminogen Activators; D012697:Serine Endopeptidases; D010959:Tissue Plasminogen Activator