Simultaneously catalyzes two reactions, namely formation of ethylene and of succinate from 2-oxoglutarate. 2-oxoglutarate + 2 H(+) + O2 = 3 CO2 + ethene + H2O 2-oxoglutarate + L-arginine + O2 = (S)-1-pyrroline-5-carboxylate + CO2 + guanidine + H(+) + H2O + succinate Alkene biosynthesis; ethylene biosynthesis via 2-oxoglutarate. Monomer. A dual-circuit mechanism has been proposed in P.syringae pv phaseolicola for the complete reaction, in which the binding of L-arginine and 2-oxoglutarate in a Schiff-base structure generates a common intermediate for the two reactions. Belongs to the iron/ascorbate-dependent oxidoreductase family.