Mechanisms of flavin cofactors for enzymatic function

FAD is a cofactor that reacts with substrates at enzyme active sites, to mediate oxidation or hydrogen removal from the substrate. During these enzymatic processes FAD and FADH2 are interconverted (these same processes are also seen with cofactors NAD+/ NADH). Recent research indicates that a hydride transfer does not occur in mechanisms involving NAD+ (from vitamin B3, niacin) or FAD. Instead the mechanism appears to be an ene reaction, similar to the Diels-Alder reaction. In the ene reaction an allyl group (ene) reacts with an alkene (enophile). Our hypothesis is that FAD is an enophile. We plan to test flavins like FAD to see if they react as enophiles with other enes. The flavin being used currently is riboflavin. Known ene, 2,3-Dimethyl-2-butene reacts with riboflavin and the product is analyzed with UV-vis spectroscopy and 1H NMR. Other enes may also be studied such as vitamin C, Dimethylpropargylamine, and β-Binene. Tetra-acetyl riboflavin can be used and lumiflavin can be synthesized to use with these enes as well. These different enes will be reacted with flavins under various conditions. Products will be isolated to help us decipher the mechanism of this reaction. This research will be ongoing in the next months and progress will be reported. We expect to confirm that the flavin is the enophile in these reactions and to discern how the intermediates form and what they are, confirming the overall mechanism.