Epoxide hydrolase of Trichoderma reesei: Biochemical properties and conformational characterization

Potential of Y. lipolytica epoxide hydrolase for efficient production of enantiopure (R)-1,2-octanediol

The recombinant Yleh from a tropical marine yeast Yarrowia lipolytica NCIM 3589 exhibited a high epoxide hydrolase activity of 9.34 ± 1.80 µmol min^-1 mg^-1 protein towards 1,2-epoxyoctane (EO), at pH 8.0 and 30 °C. The reaction product was identified as 1,2-Octanediol (OD) by GC-MS using EO and H₂O¹⁸ as substrate, affirming the functionality of Yleh as an epoxide hydrolase. For EO, the K_m, V_max, and k_cat/K_m values were 0.43 ± 0.017 mM, 0.042 ± 0.003 mM min^-1, and 467.17 ± 39.43 mM^-1 min^-1, respectively. To optimize the reaction conditions for conversion of racemic EO by Yleh catalyst to enantiopure (R)-1,2-octanediol, initially, Response Surface Methodology was employed. Under optimized reaction conditions of 15 mM EO, 150 µg purified Yleh at 30 °C a maximal diol production of 7.11 mM was attained in a short span of 65 min with a yield of 47.4%. Green technology using deep eutectic solvents for the hydrophobic substrate (EO) were tested as co-solvents in Yleh catalyzed EO hydrolysis. Choline chloride-Glycerol, produced 9.08 mM OD with an increased OD yield of 60.5%. Thus, results showed that deep eutectic solvents could be a promising solvent for Yleh-catalyzed reactions making Yleh a potential biocatalyst for the biosynthesis of enantiopure synthons.

Structural and functional characterization of the glutathione peroxidase-like thioredoxin peroxidase from the fungus Trichoderma reesei

Glutathione peroxidases (GPx) are a family of enzymes with the ability to reduce organic and inorganic hydroperoxides to the corresponding alcohols using glutathione or thioredoxin as an electron donor. Here, we report the functional and structural characterization of a GPx identified in Trichoderma reesei (TrGPx). TrGPx was recombinantly expressed in a bacterial host and purified using affinity. Using a thioredoxin coupled assay, TrGPx exhibited activity of 28 U and 12.5 U in the presence of the substrates H₂O₂ and t-BOOH, respectively, and no activity was observed when glutathione was used. These results indicated that TrGPx is a thioredoxin peroxidase and hydrolyses H₂O₂ better than t-BOOH. TrGPx kinetic parameters using a pyrogallol assay resulted at K_mapp = 11.7 mM_, V_maxapp = 10.9 IU/μg TrGPx, k_cat = 19 s^-1 and a catalytic efficiency of 1.6 mM^-1 s^-1 to H₂O₂ as substrate. Besides that, TrGPx demonstrated an optimum pH ranging from 9.0-12.0 and a half-life of 36 min at 80 °C. TrGPx 3D-structure was obtained in a reduced state and non-catalytic conformation. The overall fold is similar to the other phospholipid-hydroperoxide glutathione peroxidases. These data contribute to understand the antioxidant mechanism in fungi and provide information for using antioxidant enzymes in biotechnological applications.

Greatly enhancing the enantioselectivity of PvEH2, a Phaseolus vulgaris epoxide hydrolase, towards racemic 1,2-epoxyhexane via replacing its partial cap-loop

To achieve the kinetic resolution and enantioconvergent hydrolysis of rac-1,2-epoxyhexane, the E value of PvEH2 was enhanced by substituting its partial cap-loop. Based on the experimental results reported previously and computer-aided analysis, the flexible and variable cap-loop, especially its middle segment, was speculated to be related to the catalytic properties of PvEH2. In view of this, four PvEH2's hybrids, Pv2St, Pv2Pv1, Pv2Vr1 and Pv2Vr2, were designed by substituting the middle segment (¹⁹⁰EGMGSNLNTSMP²⁰¹) of a cap-loop in PvEH2 with the corresponding ones in StEH, PvEH1, VrEH1 and VrEH2, respectively. Then, the hybrid-encoding genes, pv2st, pv2pv1, pv2vr1 and pv2vr2, were constructed by fusion PCR, and expressed in E. coli Rosetta(DE3). The expressed hybrid, Pv2St, displayed the highest specific activity of 35.3 U/mg protein towards rac-1,2-epoxyhexane. The corresponding transformant, E. coli/pv2st, exhibited the largest E value of 24.2, which was 11.5-fold that of E. coli/pveh2 expressing PvEH2. The scale-up kinetic resolution of 280 mM rac-1,2-epoxyhexane was carried out using 40 mg dry cells/mL of E. coli/pv2st at 25 °C for 4.5 h, retaining (S)-1,2-epoxyhexane with >99.5% ee_s and 36.9% yield. Additionally, the chemo-enzymatic enantioconvergent hydrolysis of rac-1,2-epoxyhexane using E. coli/pv2st followed by sulfuric acid produced (R)-hexane-1,2-diol with 73.0% ee_p and 86.5% yield.

Eco-friendly Transformation of Waste Biomass to Biofuels

Background:

The development of viable alternative fuel sources is assuming a new urgency in the face of climate change and environmental degradation linked to the escalating consumption of fossil fuels. Lignocellulosic biomass is composed primarily of high-energy structural components such as cellulose, hemicellulose and lignin. The transformation of lignocellulosic biomass to biofuels requires the application of both pretreatment and conversion technologies.

Methods:

Several pretreatment technologies (e.g. physical, chemical and biological) are used to recover cellulose, hemicellulose and lignin from biomass and begin the transformation into biofuels. This paper reviews the thermochemical (e.g. pyrolysis, gasification and liquefaction), hydrothermal (e.g. subcritical and supercritical water gasification and hydrothermal liquefaction), and biological (e.g. fermentation) conversion pathways that are used to further transform biomass feedstocks into fuel products.

Results:

Through several thermochemical and biological conversion technologies, lignocellulosic biomass and other organic residues can produce biofuels such as bio-oils, biochar, syngas, biohydrogen, bioethanol and biobutanol, all of which have the potential to replace hydrocarbon-based fossil fuels.

Conclusions:

This review paper describes the conversion technologies used in the transformation of biomass into viable biofuels. Biofuels produced from lignocellulosic biomass and organic wastes are a promising potential clean energy source with the potential to be carbon-neutral or even carbonnegative.

The molecular structure of an epoxide hydrolase from Trichoderma reesei in complex with urea or amide-based inhibitors

Epoxide hydrolases (EHs) are enzymes involved in the metabolism of endogenous and exogenous epoxides, and the development of EH inhibitors has important applications in the medicine. In humans, EH inhibitors are being tested in the treatment of cardiovascular diseases and show potent anti-inflammatory effects. EH inhibitors are also considerate promising molecules against infectious diseases. EHs are functionally very well studied, but only a few members have its three-dimensional structures characterized. Recently, a new EH from the filamentous fungi Trichoderma reseei (TrEH) was reported, and a series of urea or amide-based inhibitors were identified. In this study, we describe the crystallographic structures of TrEH in complex with five different urea or amide-based inhibitors with resolutions ranging from 2.6 to 1.7 Å. The analysis of these structures reveals the molecular basis of the inhibition of these compounds. We could also observe that these inhibitors occupy the whole extension of the active site groove and only a few conformational changes are involved. Understanding the structural basis EH interactions with different inhibitors might substantially contribute for the study of fungal metabolism and in the development of novel and more efficient antifungal drugs against pathogenic Trichoderma species.

Substrate and inhibitor selectivity, and biological activity of an epoxide hydrolase from Trichoderma reesei

Epoxide hydrolases (EHs) are present in all living organisms and catalyze the hydrolysis of epoxides to the corresponding vicinal diols. EH are involved in the metabolism of endogenous and exogenous epoxides, and thus have application in pharmacology and biotechnology. In this work, we describe the substrates and inhibitors selectivity of an epoxide hydrolase recently cloned from the filamentous fungus Trichoderma reesei QM9414 (TrEH). We also studied the TrEH urea-based inhibitors effects in the fungal growth. TrEH showed high activity on radioative and fluorescent surrogate and natural substrates, especially epoxides from docosahexaenoic acid. Using a fluorescent surrogate substrate, potent inhibitors of TrEH were identified. Interestingly, one of the best compounds inhibit up to 60% of T. reesei growth, indicating an endogenous role for TrEH. These data make TrEH very attractive for future studies about fungal metabolism of fatty acids and possible development of novel drugs for human diseases.

Data set of optimal parameters for colorimetric red assay of epoxide hydrolase activity

The data presented in this article are related to the research article entitled "Epoxide hydrolase of Trichoderma reesei: Biochemical properties and conformational characterization" [1]. Epoxide hydrolases (EHs) are enzymes that catalyze the hydrolysis of epoxides to the corresponding vicinal diols. This article describes the optimal parameters for the colorimetric red assay to determine the enzymatic activity, with an emphasis on the characterization of the kinetic parameters, pH optimum and thermal stability of this enzyme. The effects of reagents that are not resistant to oxidation by sodium periodate on the reactions can generate false positives and interfere with the final results of the red assay.