An activity transition from NADH dehydrogenase to NADH oxidase during protein denaturation

A decrease in the specific activity of an enzyme is commonly observed when the enzyme is inappropriately handled or is stored over extended period. Here, we reported a functional transition of a FMN-bound diaphorase (FMN-DI) that happened during the long-term storage process. It was found that FMN-DI did not simply lose its NADH dehydrogenase activity after a long-time storage, but obtained a new enzyme activity of NADH oxidase. Further mechanistic studies suggested that the alteration of the binding strength of a FMN cofactor with a DI protein could be responsible for this functional switch of the enzyme. This article is protected by copyright. All rights reserved