Solvent isotope and viscosity effects on the steady‐state kinetics of the flavoprotein nitroalkane oxidase

摘要

Theflavoproteinnitroalkaneoxidasecatalyzestheoxidativedenitrificationofabroadrangeofprimaryandsecondarynitroalkanestoyieldtherespectivealdehydesorketones,hydrogenperoxideandnitrite.WithnitroethaneassubstratetheD2O(kcat/KM)valueis0.6andtheD2Okcatvalueis2.4.Thekcatprotoninventoryisconsistentwithasingleexchangeableprotoninflight,whilethekcat/KMisconsistentwitheitherasingleprotoninflightinthetransitionstateoramediumeffect.Increasingthesolventviscositydidnotaffectthekcatorkcat/KMvaluesignificantly,establishingthatnitroethanebindingisatequilibriumandthatproductreleasedoesnotlimitkcat...