@misc{BabotRioCanellasetal., author = {Babot, Esteban D. and R{\´i}o, Jos{\´e} C. del and Ca{\~n}ellas, Marina and Sancho, Ferran and Lucas, F{\´a}tima and Guallar, V{\´i}ctor and Kalum, Lisbeth and Lund, Henrik and Gr{\"o}be, Glenn and Scheibner, Katrin and Ullrich, Ren{\´e} and Hofrichter, Martin and Mart{\´i}nez, Angel T. and Guti{\´e}rrez, Ana}, title = {Steroid hydroxylation by basidiomycete peroxygenases: A combined experimental and computational study}, series = {Applied and Environmental Microbiology}, volume = {81}, journal = {Applied and Environmental Microbiology}, number = {12}, issn = {0099-2240}, doi = {10.1128/AEM.00660-15}, pages = {4130 -- 4142}, abstract = {The goal of this study is the selective oxyfunctionalization of steroids under mild and environmentally-friendly conditions using fungal enzymes. With this purpose, peroxygenases from three basidiomycete species were tested for hydroxylation of a variety of steroidal compounds, using H2O2 as the only cosubstrate. Two of them are wild-type enzymes from Agrocybe aegerita and Marasmius rotula, and the third one is a recombinant enzyme from Coprinopsis cinerea. The enzymatic reactions on free and esterified sterols, and steroid hydrocarbons and ketones were followed by gas chromatography, and the products were identified by mass spectrometry. Hydroxylation at the side chain over the steroidal rings was preferred, with the 25-hydroxyderivatives predominating (interestingly antiviral and other biological activities of 25-hydroxycholesterol have been recently reported). However, hydroxylation in the ring moiety and terminal hydroxylation at the side-chain was also observed in some steroids, the former favored by the absence of oxygenated groups at C3 and by the presence of conjugated double bonds in the rings. To understand the yield and selectivity differences between the different steroids, a computational study was performed using Protein Energy Landscape Exploration (PELE) software for dynamic ligand diffusion. These simulations showed that the active site geometry and hydrophobicity favors the entrance of the steroid side-chain, while the entrance of the ring is energetically penalized. Also, a direct correlation between the conversion rate and the side-chain entrance ratio could be established, that explains the varying reaction yields observed.}, language = {en} } @misc{PorajKobielskaPeterLeonhardtetal., author = {Poraj-Kobielska, Marzena and Peter, Sebastian and Leonhardt, Sabrina and Ullrich, Ren{\´e} and Scheibner, Katrin and Hofrichter, Martin}, title = {Immobilization of unspecific peroxygenases (EC 1.11.2.1) in PVA/PEG gel and hollow fiber modules}, series = {Biochemical Engineering Journal}, volume = {98}, journal = {Biochemical Engineering Journal}, issn = {1369-703X}, doi = {10.1016/j.bej.2015.02.037}, pages = {144 -- 150}, abstract = {The immobilization of enzymes has many advantages, such as higher stability, easier handling, and reuse of the catalyst. Here we report, for the first time, two effective methods for the immobilization of unspecific peroxygenase (UPO; EC 1.11.2.1). This biocatalyst type comprises heavily glycosylated heme-thiolate proteins that catalyze various biotechnologically relevant oxyfunctionalizations. Both the encapsulation in cryogel and the retention of the enzyme in hollow fiber modules were found to be efficient methods for their immobilization. After encapsulation, the enzyme still exhibited 60\% of its initial activity. Interestingly, we did not find differences in the kinetic parameters of free and immobilized UPOs. In long-term experiments, the conversion of the pharmaceutical diclofenac with immobilized UPOs in different reactor types yielded between 62 mg and 154 mg of the major human drug metabolite 4′-hydroxydiclofenac. The maximal total turnover number was about 60-fold higher compared to the free enzyme. A test over 5 months showed that storage of encapsulated UPOs in non-polar solvents (e.g., cyclohexane) helps to preserve the enzyme stability and increases their relative activity (by about ∼150\%, in the case of diclofenac hydroxylation). In addition to the hydrophilic substrate diclofenac, encapsulated UPOs also oxidized the hydrophobic model compound cyclohexane.}, language = {en} }