A peroxygenase-catalysed hydroxylation of organosilanes is reported. The recombinant peroxygenase from Agrocybe aegerita (AaeUPO) enabled efficient conversion of a broad range of silane starting materials in attractive productivities (up to 300 mM h⁻¹), catalyst performance (up to 84 s⁻¹ and more than 120 000 catalytic turnovers). Molecular modelling of the enzyme-substrate interaction puts a basis for the mechanistic understanding of AaeUPO selectivity.

Heme-dependent oxygenases (i.e. P450 monooxygenases and peroxygenases) are highly selective catalysts for the selective oxyfunctionalisation or organic compounds. Both enzyme classes exhibit mechanistic similarities (i.e. using so-called compound I (CpdI) as active oxidation species) and differences in how CpdI is formed. From the differences also practical differences arise which may influence the scalability, economic attractiveness and environmental impact of P450 monooxygenase- or peroxygenase-catalysed reactions. In this contribution we propose a range of performance indicators to compare the potential of both enzyme classes.

In this study, we developed a new bienzymatic reaction to produce enantioenriched phenylethanols. In a first step, the recombinant, unspecific peroxygenase from Agrocybe aegerita (rAaeUPO) was used to oxidise ethylbenzene and its derivatives to the corresponding ketones (prochiral intermediates) followed by enantioselective reduction into the desired (R)- or (S)-phenylethanols using the (R)-selective alcohol dehydrogenase (ADH) from Lactobacillus kefir (LkADH) or the (S)-selective ADH from Rhodococcus ruber (ADH-A). In a one-pot two-step cascade, 11 ethylbenzene derivatives were converted into the corresponding chiral alcohols at acceptable yields and often excellent enantioselectivity.

This paper outlines the immobilization of the recombinant dimeric unspecific peroxygenase from Agrocybe aegerita (rAaeUPO). The enzyme was quite stable (remaining unaltered its activity after 35 h at 47^◦C and pH 7.0). Phosphate destabilized the enzyme, while glycerol stabilized it. The enzyme was not immobilized on glyoxyl-agarose supports, while it was immobilized albeit in inactive form on vinyl-sulfone-activated supports. rAaeUPO immobilization on glutaraldehyde pre-activated supports gave almost quantitative immobilization yield and retained some activity, but the biocatalyst was very unstable. Its immobilization via anion exchange on PEI supports also produced good immobilization yields, but the rAaeUPO stability dropped. However, using aminated agarose, the enzyme retained stability and activity. The stability of the immobilized enzyme strongly depended on the immobilization pH, being much less stable when rAaeUPO was adsorbed at pH 9.0 than when it was immobilized at pH 7.0 or pH 5.0 (residual activity was almost 0 for the former and 80% for the other preparations), presenting stability very similar to that of the free enzyme. This is a very clear example of how the immobilization pH greatly affects the final biocatalyst performance.

The chemoenzymatic oxidative decarboxylation of glutamic acid to the corresponding nitrile using the vanadium chloroperoxidase from Curvularia inaequalis (CiVCPO) as HOBr generation catalysts has been investigated. Product inhibition was identified as major limitation. Nevertheless, 1630000 turnovers and k_cat of 75 s⁻¹ were achieved using 100 mM glutamate. The semi-preparative enzymatic oxidative decarboxylation of glutamate was also demonstrated.