Oxygen rebound mechanism
Inbiochemistry,theoxygen rebound mechanismis the pathway forhydroxylationoforganic compoundsby iron-containingoxygenases.Many enzymes effect the hydroxylation of hydrocarbons as a means for biosynthesis, detoxification, gene regulation, and other functions. These enzymes often utilizeFe-O centersthat convert C-H bonds into C-OH groups. The oxygen rebound mechanism starts with abstraction of H from the hydrocarbon, giving an organic radical and an iron hydroxide. In the rebound step, the organic radical attacks the Fe-OH center to give an alcohol group, which is bound to Fe as a ligand. Dissociation of the alcohol from the metal allows the cycle to start anew. This mechanistic scenario is an alternative to the direct insertion of an O center into a C-H bond. The pathway is an example ofC-H activation.[1][2]
Three main classes of these enzymes arecytochrome P450,alpha-ketoglutarate-dependent hydroxylases,and nonheme-diiron hydroxylases.
References
[edit]- ^Huang, X.;Groves,J. T. (2017)."Beyond ferryl-mediated hydroxylation: 40 years of the rebound mechanism and C–H activation".Journal of Biological Inorganic Chemistry.22(2–3): 185–207.doi:10.1007/s00775-016-1414-3.PMC5350257.PMID27909920.
- ^Oxygenation reactions by high-valent iron-oxo species are "C–H activation" reactions in the broad sense of the term. Some authors would call this a C–Hfunctionalizationbut not an "activation" (in its narrow sense), since a metal–carbon bond is not involved in the C–H bond cleaving process.