Interaction of a plasminogen activator proteinase, LV-PA with human alpha2-macroglobulin.
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.
Hermogenes
Ana L
AL
Research and Development Center, Ezequiel Dias Fundation, 30510-010 Belo Horizonte, MG, Brazil.
Richardson
Michael
M
Magalhaes
Arinos
A
Yarleque
Armando
A
Rodriguez
Edith
E
Sanchez
Eladio F
EF
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*
D003435:Crotalid Venoms; C072644:Lachesis venom; D000979:alpha-2-Antiplasmin; D000511:alpha-Macroglobulins; D010960:Plasminogen Activators; D012697:Serine Endopeptidases; D010959:Tissue Plasminogen Activator