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 an antioxidant activity, reducing 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 OYE3. Present with 15100 molecules/cell in log phase SD medium. Belongs to the NADH:flavin oxidoreductase/NADH oxidase family.