Search Results (636)

Naringinase consists of two enzymes: α-L-rhamnosidase and β-D-glucosidase. The enzyme was immobilized on a carrier prepared from carob gum activated with polyethyleneimine. Cross-linking with dextran aldehyde was used to improve the stability of the immobilization. Knowledge of the characteristics of naringinase subunits is important for developing efficient and selective enzymatic reactions involving flavonoids. This study aimed to characterize two subunits of naringinase—α-L-rhamnosidase and β-D-glucosidase—free, immobilized on a magnetic polysaccharide carrier and cross-linked with dextran aldehyde. The characterization of free, immobilized, and stabilized naringinase, as well as α-L-rhamnosidase and β-D-glucosidase, included the effect of pH and temperature on enzyme activity, as well as the determination of their stability depending on the pH and temperature of the environment, and the determination of kinetic constants. Immobilization and subsequent stabilization of naringinase did not affect the optimal pH for the activity of α-L-rhamnosidase and β-D-glucosidase. Immobilization caused a change in the optimal temperature for the activity of α-L-rhamnosidase and β-D-glucosidase from 60 to 65°. Cross-linking of immobilized naringinase with dextran aldehyde increased the temperature stability of its subunits. Cross-linking also altered the pH stability profile of β-D-glucosidase. Immobilization and stabilization of naringinase slightly reduced the maximum reaction rate for α-L-rhamnosidase and β-D-glucosidase compared to the free enzyme. As a result of immobilization, the enzymes’ affinity for substrates for both subunits decreased. Full article

Fungal laccases are promising oxidative enzymes for bioremediation applications, particularly in the degradation of synthetic dyes present in industrial effluents. Here, we evaluated the inhibitory effects of sodium chloride (NaCl) and sodium sulfate (Na₂SO₄) on the activity of Trametes versicolor laccase and its ability to decolorize Congo Red (CR), Malachite Green (MG), and Remazol Brilliant Blue R (RBBR). Enzyme assays revealed concentration-dependent inhibition, with IC₅₀ values of 0.22 ± 0.04 M for NaCl and 1.00 ± 0.09 M for Na₂SO₄, indicating stronger inhibition by chloride. Kinetic modeling showed mixed-type inhibition for both salts. Despite this effect, the enzyme maintained significant activity: after 12 h, decolorization efficiencies reached 95 ± 4.0% for MG, 88 ± 3.0% for RBBR, and 75 ± 3.0% for CR, even in the presence of 0.5 M salts. When applied to a mixture of the three dyes, decolorization decreased only slightly in saline medium (94.04 ± 4.0% to 83.43 ± 5.1%). FTIR spectra revealed minor structural changes, but toxicity assays confirmed marked detoxification, with radicle length in lettuce seeds increasing from 20–38 mm (untreated dyes) to 41–48 mm after enzymatic treatment. Fungal growth assays corroborated reduced toxicity of treated dyes. These findings demonstrate that T. versicolor laccase retains functional robustness under ionic stress, supporting its potential application in saline textile wastewater remediation. Full article

Bisphenol A (BPA) is classified as an endocrine disruptor that mainly mimics the effects of estrogen and disrupts the synthesis of male androgens. Due to the toxicity of BPA, some new analogs, such as bisphenol BPB, BPC, BPF, PBH, and BPZ, were introduced into the market. The goal of this research was to demonstrate the applicability of kinetic analysis, in particular, Lineweaver-Burk plots, in assessing the impact of bisphenol Z on enzymatic activity. This study aimed to characterize the inhibitory effects of BPZ on 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) activity in the transformation of 11-dehydrocorticosterone (DHC) to corticosterone (CORT). During the determination of the enzymatic reaction product, chromatographic analysis conditions were optimized using gradient elution and an Acquity UPLC BEH C18 chromatographic column. The retention time of the assayed corticosterone was approximately 2 min. Also described and compared were graphical methods of analysis and data interpretation, such as Lineweaver-Burk, Eadie-Hofstee, and Hanes-Woolf plots. The experiments demonstrated that bisphenol Z is a mixed 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) inhibitor, responsible for catalyzing the conversion of 11-dehydrocorticosterone (DHC) to corticosterone (CORT). This relationship was confirmed by analyzing Lineweaver-Burk plots, which showed an increase in apparent K_M with a decrease in the constant V_max, suggesting a mixed inhibition mechanism. Molecular docking and detailed analysis of the interaction profiles revealed that BPZ consistently occupies the active site cavities of all examined enzymes (rat and human 11β-HSD1 and Arabidopsis 11β-HSD2), forming a stabilizing network of non-covalent interactions. Our research has significant biological significance considering the role of the 11β-HSD1 enzyme in the conversion of DHC to CORT and the importance of this process and its functions in adipose tissue, the liver, and the brain. Full article

Photocatalytic nitrogen fixation under ambient conditions offers a sustainable alternative to the energy-intensive Haber–Bosch process, yet remains limited by the inertness of N≡N bonds and sluggish multi-electron/proton transfer kinetics. Nature’s nitrogenase enzymes, featuring the FeMo cofactor and ATP-driven electron cascades, inspire a new generation of artificial systems capable of mimicking their catalytic precision and selectivity. This review systematically summarizes recent advances in bio-inspired photocatalytic nitrogen reduction, focusing on six key strategies derived from enzymatic mechanisms: Fe–Mo–S active site reconstruction, hierarchical electron relay pathways, ATP-mimicking energy modules, defect-induced microenvironments, interfacial charge modulation, and spatial confinement engineering. While notable progress has been made in enhancing activity and selectivity, challenges remain in dynamic regulation, mechanistic elucidation, and system-level integration. Future efforts should prioritize operando characterization, adaptive interface design, and device-compatible catalyst platforms. By abstracting nature’s catalytic logic into synthetic architectures, biomimetic photocatalysis holds great promise for scalable, green ammonia production aligned with global decarbonization goals. Full article

The tree bean (Parkia timoriana), an underutilized legume valued for its nutritional profile, represents a potential source of bioactive peptides for diabetes management. To our knowledge, this is the first study to identify and characterize DPP-IV inhibitory peptides derived from tree bean seed protein hydrolysates. The tree bean proteins were digested with trypsin, thermolysin, chymotrypsin, pepsin, and simulated gastrointestinal (SGI) enzymes, among which SGI hydrolysis yielded the highest degree of hydrolysis (14%) and strongest DPP-IV inhibitory activity (IC₅₀ = 1289 ± 58 µg/mL). Guided by DPP-IV inhibitory assays, sequential fractionation using strong cation exchange and RP-HPLC yielded the most potent fraction, H5, with an IC₅₀ of 949 ± 50 µg/mL. After peptide identification and synthesis, APLGPF (AF6) emerged as the most potent inhibitor, with an IC₅₀ of 396 ± 18 µM. Enzyme kinetics revealed a non-competitive inhibition mechanism, corroborated by molecular docking, which indicated binding at an allosteric site of DPP-IV. Furthermore, AF6 remained stable under simulated gastrointestinal digestion and enzymatic exposure, highlighting its resistance to proteolysis. Taken together, these findings highlight P. timoriana as an underexplored source of peptides with DPP-IV inhibitory activity and identify AF6 as a promising lead for developing functional foods or nutraceuticals aimed at type 2 diabetes management. Full article

Drying critically shapes tofu’s texture, structure, and final appearance, whether it occurs during cooking or is applied intentionally in reprocessing. This study aimed to characterize the drying kinetics of tofu through experimental analysis and through modeling. Tofu samples were dried at temperatures ranging from 40 °C to 90 °C using a convective drying tunnel and an oven. Shrinkage and color changes were analyzed. Empirical models, a shrinking-core model and a newly developed oven-cooking model were tested against experimental data. The drying kinetics exhibited a constant and a decreasing rate phase, which were separated by a water content threshold of 2.56 ${\mathrm{kg}}_{\mathrm{W}}/{\mathrm{kg}}_{\mathrm{DS}}$. Tofu undergoes non-enzymatic browning and exhibited total shrinkage of 0.38. These physical changes were more significant at lower drying temperatures when the product was dried below a water content of 1.39 ${\mathrm{kg}}_{\mathrm{W}}/{\mathrm{kg}}_{\mathrm{DS}}$. The logarithmic model provided the best fit (${\mathrm{R}}^2\ge 0.9920$) to the experimental data. However, the cooking model shows good results as well (${\mathrm{R}}^2=0.9678$) and offers physical validity. This study provides evidence that the drying mechanisms of tofu are not temperature-dependent within the studied range. It also emphasizes the importance of drying time over drying temperature in the physical changes of the product. The successful fit of the cooking model highlights the link between drying and cooking processes, suggesting potential applications in both areas. Full article

The study of protein enzymatic activities has always been a significant area of scientific and industrial research. The key steps typically undertaken in the characterization of a certain enzyme family include establishing the mechanism of catalysis, measuring kinetic parameters, determining structural organization and the architecture of the catalytic center, and subsequent classification. In this review, we tried to touch upon only a few points from the classical description of enzymes of the dUTPase family and added some additional functional properties of a number of representatives of this family. The existence of such extra functions raises questions about the reasons for this function duality. Based on the information known in the literature and our previous research, in this review, we conclude that the enzymatic activity of dUTPases supplements other functions independent of the hydrolysis reaction occurring in the catalytic center. In this context, it seems that dUTP acts not just as a substrate but as a signaling molecule, whose binding induces the realization of a special, non-enzymatic role of dUTPases. Full article

Background: Multitarget-directed ligands (MTDLs), particularly those combining cholinesterase inhibition with additional mechanisms, are promising candidates for Alzheimer’s disease (AD) therapy. Based on our previous identification of a dual-active coumarin derivative, we designed a new series of 7-alkoxyamino-3-(1,2,3-triazole)-coumarins. Methods: These compounds were synthesized by a new Sonogashira protocol and evaluated for AChE and BChE inhibition, enzymatic kinetics, molecular docking, neurotoxicity in SH-SY5Y cells, neuroprotection against H₂O₂-induced oxidative stress, and additional interactions with H₃R and MAOs. Results: All derivatives inhibited AChE with IC₅₀ values of 4–104 nM, displaying high selectivity over BChE (up to 686-fold). Kinetic and docking studies indicated mixed-type inhibition involving both CAS and PAS. The most potent compounds (1h, 1j, 1k, 1q) were non-neurotoxic up to 50 µM, while 1h and 1k also showed neuroprotective effects at 12.5 µM. Selected derivatives (1b, 1h, 1q) demonstrated multitarget potential, including H₃R affinity (K_i as low as 32 nM for 1b) and MAO inhibition (IC₅₀ of 1688 nM for 1q). Conclusions: This series of coumarin–triazole derivatives combines potent and selective AChE inhibition with neuroprotective and multitarget activities, highlighting their promise as candidates for AD therapy. Full article

Research into oral mucosa-targeted drug delivery systems (DDS) is rapidly evolving, with growing emphasis on enhancing bioavailability and precision targeting while overcoming the unique anatomical and physiological barriers of the oral environment. Despite considerable progress, challenges such as enzymatic degradation, limited mucosal penetration, and solubility issues continue to hinder therapeutic success. Recent advancements have focused on innovative formulation strategies—including nanoparticulate and biomimetic systems—to improve delivery efficiency and systemic absorption. Simultaneously, smart and stimuli-responsive materials are emerging, offering dynamic, environment-sensitive drug release profiles. One particularly promising area involves the application of glycosaminoglycans, a class of naturally derived polysaccharides with excellent biocompatibility, mucoadhesive properties, and hydrogel-forming capacity. These materials not only enhance drug residence time at the mucosal site but also enable controlled release kinetics, thereby improving therapeutic outcomes. However, critical research gaps remain: standardized, clinically meaningful mucoadhesion/permeation assays and robust in vitro–in vivo correlations are still lacking; long-term stability, batch consistency of GAGs, and clear regulatory classification (drug, device, or combination) continue to impede scale-up and translation. Patient-centric performance—palatability, mouthfeel, discreet wearability—and head-to-head trials versus standard care also require systematic evaluation to guide adoption. Overall, converging advances in GAG-based films, hydrogels, and nanoengineered carriers position oral mucosal delivery as a realistic near-term option for precision local and selected systemic therapies—provided the field resolves standardization, stability, regulatory, and usability hurdles. Full article

Glycerol-3-phosphate acyltransferases (GPATs) catalyze the initial and rate-limiting step of glycerolipid biosynthesis, yet their contribution to salt tolerance in the soybean (Glycine max (L.) Merr.) plants remains largely uncharacterized. In this study, a total of 27 GmGPAT genes were identified, and their evolutionary relationships, chromosomal distribution, conserved motifs, and cis-regulatory elements were comprehensively analyzed. Through transcriptomic and qPCR analyses, many GmGPATs were found to be predominantly expressed in roots, with GmGPAT1, a plastid-targeted isoform, displaying the most rapid and pronounced transcriptional activation under salt stress. GFP-fusion experiments in transient expression assays confirmed plastid localization of GmGPAT1. Heterologous expression in Escherichia coli together with enzyme kinetics analyses validated its enzymatic function as a GPAT family member. The soybean hairy-root lines overexpressing GmGPAT1 exhibited enhanced root elongation, increased biomass, and improved photosynthetic efficiency under 120 mM NaCl stress, while CRISPR/Cas9 knockout mutants showed pronounced growth inhibition. Physiological assays demonstrated that GmGPAT1 overexpression mitigated oxidative damage by limiting reactive oxygen species (ROS) accumulation and lipid peroxidation, increasing antioxidant enzyme activities (CAT, SOD, POD), and elevating the ratios of AsA/DHA and GSH/GSSG. These changes contributed to redox homeostasis and improved Na⁺ extrusion capacity. A genome-wide association study (GWAS) involving 288 soybean accessions identified a single nucleotide polymorphism in the GmGPAT1 promoter that was significantly correlated with salt tolerance, and the beneficial Hap1 allele emerged as a promising molecular marker for breeding. Together, these analyses emphasize the status of GmGPAT1 as a major regulator of salt stress adaptation through the coordinated modulation of lipid metabolism and redox balance, extend the functional annotation of the soybean GPAT family, and highlight new genetic resources that can be leveraged to enhance tolerance to salt stress in soybean cultivars. Full article

Myoglobin, a heme protein involved in oxygen storage and transport, also exhibits pseudo-peroxidase activity by catalyzing the breakdown of hydrogen peroxide. While this enzymatic function is well-documented, the potential for substrate inhibition at high hydrogen peroxide concentrations remains underexplored. In this study, we aimed to investigate the kinetic properties of myoglobin’s peroxidase-like activity, focusing on substrate inhibition over time. We employed spectrophotometric assays to monitor reaction rates of myoglobin exposed to increasing hydrogen peroxide concentrations. Our results show that myoglobin activity begins to decline within 3 min of exposure to hydrogen peroxide and reaches full inhibition after approximately 30 min. This progressive inhibition suggests that myoglobin undergoes a delayed inactivation process rather than an immediate loss of function. Additionally, we extended the investigation to hemoglobin, comparing its response to hydrogen peroxide, and preliminary data suggest differences in substrate inhibition dynamics. These findings provide new insights into the regulation of myoglobin’s oxidative function and suggest potential physiological implications for oxidative stress and redox balance, especially in relation to other heme proteins like hemoglobin. Full article

Native yeasts are a promising microbial resource for the development of sustainable biorefineries. In this study, we isolated 30 yeast strains from soil, decaying wood, and tree bark in a preserved Araucaria Forest in Southern Brazil and characterized them phenotypically and taxonomically. All strains were able to grow on glucose, xylose, and cellobiose, and 50% of them could metabolize arabinose. Several isolates showed high growth rates on xylose (up to 0.47 h⁻¹) and cellobiose (up to 0.45 h⁻¹). Notably, 19 strains (63% of the analyzed yeasts) exhibited xylanase activity at 50 °C (up to 156.84 U/mL), and four strains (13%) showed significant cellulase production. β-Glucosidase activities were particularly high in permeabilized cells of CHAP-258, CHAP-277, and CHAP-278 (up to 584.33 U/mg DCW), with kinetic parameters indicating high enzymatic performance. Twelve strains (40% of the total) were classified as oleaginous, and three (10%) displayed both lipogenic and esterase activity. Lipase activity against p-nitrophenyl palmitate (pNPP) reached 55.55 U/mL in CHAP-260. Taxonomic identification revealed representatives of seven genera, including Meyerozyma, Papiliotrema, Scheffersomyces, and Sugiyamaella, with potential for biotechnological use. Overall, the biochemical diversity observed highlights the value of native yeasts from Araucaria Forests as biocatalysts for lignocellulose-based bioprocesses, particularly due to their ability to grow on pentoses, secrete hydrolytic enzymes, and accumulate lipids. Full article

Lipases are widely used as biocatalysts in synthetic applications because of their high chemo-, regio-, and enantioselectivities, which play key roles in the synthesis of esters and the resolution of racemates. These biocatalytic steps are essential for the production of various products, including cosmetic ingredients, building blocks in the pharmaceutical and agrochemical industries. In this study, we produced lipases through solid-state fermentation of agricultural by-products and domestic wastes using the fungus Pycnoporus sanguineus. After fermentation, the dried solids containing lipases from P. sanguineus exhibited high catalytic activity. Lipase production was achieved via solid-state fermentation using a substrate composed of wheat bran and sugarcane bagasse supplemented with either residual frying oil or urea, resulting in an enzymatic activity of 24 U mL⁻¹ after 96 h. The resulting P. sanguineus fermentation solids (PSFS) efficiently catalyzed the esterification of capric acid with ethanol, achieving 95% ester conversion within 28 h. Additionally, PSFS proved to be effective in the kinetic resolution of (RS)-1-phenyl-1-ethanol via transesterification with various acyl donors, selectively forming the (R)-enantiomer. This process yielded a 16% conversion to (R)-1-phenylethyl propionate and an enantiomeric ratio (E) exceeding 200 after 72 h. These results demonstrate the potential of PSFS for applications in ester synthesis and resolution of enantiomerically pure sec-alcohols. Full article

The global gold extraction industry has been reported to use cyanide-based recovery processes, which pose environmental effects on water resources. The study examined Coptodon zillii liver rhodanese from a gold mining-impacted reservoir with a specific focus on the enzyme’s critical function in cyanide detoxification. Rhodanese was purified using successive chromatographic techniques with 5.4 U/mg specific activity and 3.1-fold purification. The molecular weight of the native enzyme was 36 kDa, and the subunits were 17 kDa, indicative of a dimeric structure. Optimal enzymatic activity was recorded at pH 8.0 and 50 °C. The effect of metal ions was significantly varied: the activity was inhibited by BaCl₂, CaCl₂, NaCl, and MgCl₂, and KCl enhanced performance. The kinetic determinations showed Michaelis-Menten kinetics with a Km of 20.0 mM for sodium thiosulfate and 25.0 mM for potassium cyanide. The enzyme’s minimal activity was identified toward 2-mercaptoethanol, ammonium persulfate, and ammonium sulfate, but with evidence of preference for thiosulfate utilization under the substrate specificity tests. The major interactions between the enzyme and the substrate were revealed by the molecular docking experiments. These showed Glu159, Gln161, and Arg173 formed important hydrogen bonds with thiosulfate, while Arg156 and Val172 were also involved. Other substrates are bound to Gln121 and Trp139 residues with much lower binding energy than thiosulfate. The findings increase our understanding of biochemical adaptation process knowledge in anthropogenically stressed environments, showing strategies of ecological resilience. The characterized enzymatic features showed potent cyanide detoxification potential, and the possible applications are in bioremediation strategies for mining-impacted aquatic ecosystems. Full article

Biohydrogen, a low-carbon footprint technology, can play a significant role in decarbonizing the energy system. It uses existing infrastructure, is easily transportable, and produces no greenhouse gas emissions. Four technologies can be used to produce biohydrogen: photosynthetic biohydrogen, dark fermentation (DF), photo-fermentation, and microbial electrolysis cells (MECs). DF produces more biohydrogen and is flexible with organic substrates, making it a sustainable method of waste repurposing. However, low achievable biohydrogen yields are a common issue. To overcome this, catalytic mechanisms, including enzymatic systems such as [Fe-Fe]- and [Ni-Fe]-hydrogenases in DF and electroactive microbial consortia in MECs, alongside advanced electrode catalysts which collectively surmount thermodynamic and kinetic constraints, and the two stage system, such as DF connection to photo-fermentation and anaerobic digestion (AD) to microbial electrolysis cells (MECs), have been investigated. MECs can generate biohydrogen at better yields by using sugars or organic acids, and combining DF and MEC technologies could improve biohydrogen production. As such, this review highlights the challenges and possible solutions for coupling DF–MEC while also offering knowledge regarding the technical and microbiological aspects. Full article