@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{BabotArandaKiebistetal., author = {Babot, Esteban D. and Aranda, Carmen and Kiebist, Jan and Scheibner, Katrin and Ullrich, Ren{\´e} and Hofrichter, Martin and Mart{\´i}nez, Angel T. and Gutierrez, Ana}, title = {Enzymatic Epoxidation of Long-Chain Terminal Alkenes by Fungal Peroxygenases}, series = {Antioxidants}, volume = {11}, journal = {Antioxidants}, number = {3}, issn = {2076-3921}, doi = {10.3390/antiox11030522}, pages = {1 -- 12}, abstract = {Terminal alkenes are among the most attractive starting materials for the synthesis of epoxides, which are essential and versatile intermediate building blocks for the pharmaceutical, flavoring, and polymer industries. Previous research on alkene epoxidation has focused on the use of several oxidizing agents and/or different enzymes, including cytochrome P450 monooxygenases, as well as microbial whole-cell catalysts that have several drawbacks. Alternatively, we explored the ability of unspecific peroxygenases (UPOs) to selectively epoxidize terminal alkenes. UPOs are attractive biocatalysts because they are robust extracellular enzymes and only require H2O2 as cosubstrate. Here, we show how several UPOs, such as those from Cyclocybe (Agrocybe) aegerita (AaeUPO), Marasmius rotula (MroUPO), Coprinopsis cinerea (rCciUPO), Humicola insolens (rHinUPO), and Daldinia caldariorum (rDcaUPO), are able to catalyze the epoxidation of long-chain terminal alkenes (from C12:1 to C20:1) after an initial optimization of several reaction parameters (cosolvent, cosubstrate, and pH). In addition to terminal epoxides, alkenols and other hydroxylated derivatives of the alkenes were formed. Although all UPOs were able to convert and epoxidize the alkenes, notable differences were observed between them, with rCciUPO being responsible for the highest substrate turnover and MroUPO being the most selective with respect to terminal epoxidation. The potential of peroxygenases for epoxidizing long-chain terminal alkenes represents an interesting and green alternative to the existing synthesis technologies.}, language = {en} }