Destruction of vitamin K1 of cultured carrot cells by ultraviolet radiation and its effect on plasma membrane electron transport reactions.

The effect of ultraviolet radiation on plasma membrane electron transport reactions was studied in cultured carrot cells. It was found that a 90 min treatment inhibited transmembrane hexacyanoferrate reduction greater than 50%. Extraction of lipophilic quinones from irradiated cells showed that vitamin K1 and coenzyme Q were totally destroyed, while control unirradiated cells showed the presence of 0.4 mumole vitamin K1 g dry wt.-1. The addition of exogenous vitamin K1 in concentrations of 1-10 microM partially restored plasma membrane electron transport with impermeable hexacyanoferrate as the electron acceptor. Total restoration of activity was given by growing irradiated cells in vitamin K1 supplemented growth media for 6 days. This shows that vitamin K1 may function as a member of the transplasma membrane electron transport chain in cultured carrot cells.