Flavin-dependent enoate reductase that catalyzes the chemo- and stereoslective hydrogenation of electron-poor alkenes. The enzyme is reduced by NADPH, and oxygen, quinones, and alpha,beta-unsaturated aldehydes and ketones can act as electron acceptors to complete catalytic turnover. The physiological oxidant remains elusive (By similarity). Has a prooxidant activity, increasing reactive oxygen species (ROS) levels when overexpressed. Formation of OYE2-OYE3 heterodimers contribute to the induction of programmed cell death upon oxidative stress (PubMed:17897954). A + H(+) + NADPH = AH2 + NADP(+) Homodimer or heterodimer with OYE2. Belongs to the NADH:flavin oxidoreductase/NADH oxidase family.