Fig. 18. Reaction catalyzed by dihydrooroate dehydrogenase. In the pyrimidine-half reaction the FMN cofactor is reduced by transfer of a hydride to the N(5)-position of the isoalloxazine ring (highlighted in red) followed by proton abstraction from the 5-position of dihydroorotate. A. thaliana dihydrooroate dehydrogenase belongs to the class 2 enzymes that are localized in the inter membrane space and associated with the inner mitochondrial membrane. Thus, reoxidation occurs by two successive one-electron transfer steps from the reduced FMN to CoQ (shown here as a single step). For a detailed discussion on the reaction mechanism see Palfey (2013). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Published as part of Eggers, Reinmar, Jammer, Alexandra, Jha, Shalinee, Kerschbaumer, Bianca, Lahham, Majd, Strandback, Emilia, Toplak, Marina, Wallner, Silvia, Winkler, Andreas & Macheroux, Peter, 2021, The scope of flavin-dependent reactions and processes in the model plant Arabidopsis thaliana, pp. 1-42 in Phytochemistry (112822) 189 on page 13, DOI: 10.1016/j.phytochem.2021.112822, http://zenodo.org/record/8259454