Oxygenases, asymmetric oxidation

Hewgley, B., Stahl S. and Kozlowski, M. (2008). Mechanistic Study of Asymmetric Oxidative Biaryl Coupling evidence for Self-Processing of the Copper Catalyst to Achieve Control of Oxidase vs Oxygenase Activity, J. Am. Chem. Soc., 130, pp. 12232-12233. 

Recently, the first asymmetric cell-free application of styrene monooxygenase (StyAB) from Pseudomonas sp. VLB 120 was reported [294]. StyAB catalyses the enantiospecific epoxidation of styrene-type substrates and requires the presence of flavin and NADH as cofactor. This two-component system enzyme consists of the actual oxygenase subunit (StyA) and a reductase (StyB). In this case, the reaction could be made catalytic with respect to NADH when formate together with oxygen were used as the actual oxidant and sacrificial reductant respectively. The whole sequence is shown in Fig. 4.106. The total turnover number on StyA enzyme was around 2000, whereas the turnover number relative to NADH ranged from 66 to 87. Results for individual substrates are also given in Fig. 4.106. Excellent enantioselectivities are obtained for a- and -styrene derivatives. 

More recently, research concerning catalytic oxidation reactions has emerged on one side from bioinorganic chemistry with cytochrome P450 models and non-por-phyrinic methane mono-oxygenase models, and on the other side, from organic chemistry with asymmetric epoxidation and dihydroxylation. 

---