Carbon Acid Oxidations and Oxygen Activation by Flavins

Evidence is presented in support of free-radical mechanisms for the oxidation of ionizable carbon acids by oxidized flavin. Activation of molecular oxygen by reduced flavin is shown to occur through the formation of a 4a-hydroperoxyflavin that may, dependent upon conditions and substrate, transfer one or two oxygen atoms. Examples of all reactions are provided in the text. The present state of knowledge concerning the chemiluminescent oxidations of aldehydes by 4a-hydroperoxyflavin is considered.