IDENTIFICATION OF NONHEME DIIRON PROTEINS THAT CATALYZE TRIPLE BOND AND EPOXY GROUP FORMATION

Acetylenic bonds are present in more than 600 naturally occurring comp ounds. Plant enzymes that catalyze the formation of the Delta 12 acety lenic bond in 9-octadecen-12-ynoic acid and the Delta 12 epoxy group i n 12,13-epoxy-9-octadecenoic acid were characterized, and two genes, s imilar in sequence, were cloned. When these complementary DNAs were ex pressed in Arabidopsis thaliana, the content of acetylenic or epoxidat ed fatty acids in the seeds increased from 0 to 25 or 15 percent, resp ectively. Both enzymes have characteristics similar to the membrane pr oteins containing non-heme iron that have histidine-rich motifs.