Figure 4.

Plasminogen is converted to plasmin by uPA when bound to Vlp15/16. Microtiter plates were either coated with 5 µg/ml of plasminogen (Plg) (A) or with 5 µg/ml of purified Vlp15/16 (B), BBA70 (C) or Vsp1 (D). The plasminogen-coated wells were then incubated with (filled circle) or without uPA (filled square). The immobilized borrelial proteins were subsequently incubated with 10 µg/ml plasminogen. Following incubation uPA and the chromogenic substrate D-Val-Leu-Lys-p-nitroanilide dihydrochloride (S-2251) was added (filled circle). Control reactions included 50 mM of the lysine analog tranexamic acid (T) (filled square) or omitted plasminogen (filled triangle) or uPA (filled inverted triangle), respectively. Microtiter plates were incubated at RT for 24 h and absorbance at 405 nm was measured at 30 min intervals. At least three independent experiments were conducted, each in triplicate. Data shown are from a representative experiment.