Cytochromes P-450 catalyze the formation of marchantins A and C in Marchantia polymorpha

Two specific cytochrome P-450 enzymes were detected in cell suspension cult ures of Marchantla polymorpha; the first catalyzes the coupling of two mole cules of lunularic acid to form marchantin C and CO2 and the second hydroxy lates marchantin C to marchantin A. Cell free experiments using H-3/C-14 do ubly-labeled substrates demonstrated that lunularic acid: and neither lunul arine nor prelunularic acid, is the sole substrate for the coupling reactio n. Both enzymes are dependent on the: presence of oxygen and NADPH. Both re actions were inhibited in the presence of CO in the dark; this inhibition w as partially reversed by white light. In addition, both reactions were inhi bited by typical inhibitors of cytochrome P-450 enzymes such as cytochrome c and ancymidol. (C) 1999 Elsevier Science Ltd. All rights reserved.