Enzymatic oxygenating activity

Figure 2. Enzymatic oxygen activation in milk XO Xanthine oxidase, SOD Superoxide dismutase, LPO Lactoperoxidase.

The enzymatic oxygenation process is of particular value as there is a significant difference in the formation rates of sulfoxides and sulfones. The initial conversion of sulfide to the optically active sulfoxide by an MO is usually very fast compared to the subsequent oxidation step to sulfone, upon which chirality is lost (Scheme 9.26). In many cases, over-oxidation to sulfone is not observed at all when employing MOs. 

The stimulus for the recent surge of activity in this previously dormant area of organic chemistry can be traced to the prostaglandin connection . That is to the discovery that saturated bicyclic peroxides are key intermediates in the biosynthesis of prostaglandins and other physiologically active substances by the enzymatic oxygenation of polyunsaturated fatty acids. 

Support for the argument that the cofactor is the site for oxygen activation stems from two sets of experiments. Kaufman [105] first observed the accumulation of a transient species during PAH turnover that decays non-enzymatically or, in the presence of a stimulator protein, enzymatically to quinonoid-BPHj. Since the rate of tyrosine formation was more rapid than decay of this species, the transfer of oxygen must already be complete. This deduction led to the postulate that the intermediate is comprised of elements from both BPH4 and the remaining oxygen... 

While the active species responsible for the oxidations in the enzymatic system is still obscure. Scheme 1 summarizes a recent understanding of the oxygen activation mechanism by P-450 [1, 2]. 

R. Orru, H.M. Dudek, C. Martinoli, P.D.E. Torres, A. Royant, M. Weik, M.W. Fraaije, A. Mattevi, Snapshots of enzymatic Baeyer-Villiger catalysis oxygen activation and intermediate stabilization, J. Biol. Chem. 286 (2011) 29284-29291. 

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