What happens to flavins during electron transfer reactions?

Flavins are important coenzymes in biochemical reactions, particularly those involving electron transfer. The correct understanding of their role is that flavins, such as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), can accept electrons. However, they have a unique behavior in that they can accept one electron at a time, which means they often undergo a two-step reduction process. This is significant in redox reactions, allowing them to participate effectively in biochemical pathways.

The mechanism in which flavins accept electrons involves the formation of intermediate radical species when one electron is accepted. Therefore, it is accurate to state that flavins can only accept one electron at a time in these reactions. This characteristic distinguishes them from other electron carriers that may take two electrons simultaneously. Their ability to accept electrons in a stepwise manner contributes to their functionality in various metabolic pathways, including those related to respiration and plant photosynthesis.