Fig. 5.
Vitamin K1 and menaquinone-4 do not directly inhibit 12-lipoxygenase enzymatic activity in a cell-free system. A: Purified 12-LOX (20 U) was incubated with AA861 (10 μM) or MK-4 (10 μM) for 30 min prior to addition of the 12-LOX substrate arachidonic acid (100 μM). The reaction mix was incubated for 20 min at 37°C. 12-HETE was extracted and analyzed by thin-layer chromatography as described. Positions of origins of sample application, 12-HETE, and free arachidonic acid are indicated by arrows. B: The 12-LOX-specific inhibitor BHPP (2–20 μM) dose dependently blocked 12-HETE production. Data are from one experiment representative of three that were performed.