Search Results (219)

Candida albicans is an opportunistic fungal pathogen that can cause superficial and life-threatening infections, particularly in immunocompromised individuals. Its ability to adhere to host cells is critical for colonization and infection. In this context, investigating ectophosphatases is particularly relevant, as these enzymes have been associated with fungal adhesion to host cells. This study aimed to investigate the nature of copper-induced stimulation of ectophosphatase activity in C. albicans. Ectophosphatase activity was measured using p-nitrophenyl phosphate as substrate. Micromolar concentrations of CuCl₂ markedly stimulated ectophosphatase activity, and its response to reducing agents and metal chelators suggested that this modulation does not involve redox reactions. The significant differences between the biochemical properties of basal (Cu²⁺-independent) and Cu²⁺-dependent ectophosphatase activities suggest the presence of at least two distinct ectophosphatases in C. albicans. Cu²⁺-independent ectophosphatase activity presented an acidic profile and was insensitive to Mg²⁺, whereas Cu²⁺-dependent ectophosphatase activity exhibited an alkaline profile and was also stimulated by Mg²⁺. Both activities were negatively modulated by classical phosphatase inhibitors, but Cu²⁺-dependent ectophosphatase had lower sensitivity compared to the basal activity. These findings highlight the role of copper as a modulator of C. albicans ectophosphatase activity and suggest potential implications for fungal adaptation during infection. Full article

This short review provides an overview of the bioinorganic chemistry of molybdenum and tungsten, offering insights into current research perspectives and fundamental concepts in the field, as well as gaps in our knowledge. It is designed to highlight areas where future research is needed to fully elucidate the mechanisms of molybdenum- and tungsten-dependent enzymes and their broader significance in biochemistry and bioinorganic chemistry. It also provides an accessible introduction for senior undergraduate students and novice postgraduate researchers who are new to the field of bioinorganic chemistry. Towards this end, illustrative examples are presented, showcasing the essential roles these metals play in biological systems, their coordination chemistry, and their catalytic functions in metalloenzymes. Full article

The increasing discharge of nutrient and metal-laden effluents into saline environments demands sustainable remediation strategies. This study evaluated the phytoremediation potential of Salicornia brachiata, a halophytic plant, under hydroponic conditions using varying concentrations of three macronutrients—nitrate (NO₃⁻), phosphate (PO₄³⁻), and calcium (Ca²⁺)—and three heavy metals—lead (Pb²⁺), chromium (Cr⁶⁺), and copper (Cu²⁺). The plant exhibited high removal efficiencies across all treatments, with Pb²⁺ and Cr⁶⁺ reaching nearly 99% removal within two days, while macronutrient removal showed a steady, time-dependent increase over the 14-day period. Several biochemical parameters, including proline content and antioxidant enzyme activities (catalase, superoxide dismutase, peroxidase, polyphenol oxidase), were significantly affected by treatments, with most showing dose-dependent responses to heavy metal exposure, indicating strong biochemical resilience. Fourier transform infrared spectroscopy revealed pollutant-specific structural shifts and identified –OH, –NH, and –COO⁻ groups as key binding sites. The study quantifies the removal efficiency of S. brachiata for both nutrients and metals and provides mechanistic insight into its ionic stress response and binding pathways. These findings establish S. brachiata as a viable candidate for integrated phytoremediation in saline, contaminated water systems. Full article

Acetone carboxylase (AC) from Xanthobacter autotrophicus is a 360 KDa α₂β₂γ₂ heterohexamer that catalyzes the ATP-dependent formation of phosphorylated acetone and bicarbonate intermediates that react at Mn(II) metal active sites to form acetoacetate. Structural models of X. autotrophicus AC (XaAC) with and without nucleotides reveal that the binding and phosphorylation of the two substrates occurs ~40 Å from the Mn(II) active sites where acetoacetate is formed. Based on the crystal structures, a significant conformational change was proposed to open and close a tunnel that facilitates the passage of reaction intermediates between the sites for nucleotide binding and phosphorylation of substrates and Mn(II) sites of acetoacetate formation. We have employed electron paramagnetic resonance (EPR), kinetic assays, and hydrogen/deuterium exchange mass spectrometry (HDX-MS) of poised ligand-bound states and site-specific amino acid variants to complete an in-depth analysis of Mn(II) coordination and allosteric communication throughout the catalytic cycle. In contrast with the established paradigms for carboxylation, our analyses of XaAC suggested a carboxylate shift that couples both local and long-range structural transitions. Shifts in the coordination mode of a single carboxylic acid residue (αE89) mediate both catalysis proximal to a Mn(II) center and communication with an ATP active site in a separate subunit of a 180 kDa α₂β₂γ₂ complex at a distance of 40 Å. This work demonstrates the power of combining structural models from X-ray crystallography with solution-phase spectroscopy and biophysical techniques to elucidate functional aspects of a multi-subunit enzyme. Full article

Matrix metalloproteinases (MMPs) are key enzymes involved in the remodeling of the extracellular matrix (ECM) through the degradation of its components in a controlled endoproteolytic manner. Beyond ECM degradation, MMPs also target plasma membrane proteins implicated in signaling cascades and the progression of disease. Structurally, the catalytic function of MMPs is dependent on metal ions such as Zn²⁺. ECM remodeling by MMPs supports processes including tissue growth, morphogenesis, elongation, and adaptation to environmental changes occurring under both physiological and pathological conditions. These activities are subject to tight regulation by cellular MMP enzymes. While the current body of research has primarily centered on the functions of MMPs and their roles in cancer biology, knowledge of their involvement in vascular disease, endometriosis, fibrotic eye disease, epithelial cell differentiation, and the actions of MMP inhibitors remains comparatively sparse. This review explores the roles of MMPs in vascular disease and endometriosis, particularly as they relate to the ectopic growth of endometrial tissue. In addition, we summarize evidence regarding their contributions to disease mechanisms, with a focus on pathological progression. Due to their significant therapeutic promise in a variety of human diseases, advancing our understanding of MMP biology is likely to facilitate progress in clinical application and the development of novel interventions. This review also evaluates advances in the development and therapeutic potential of MMP inhibitors. Full article

Silicon nanoparticles (SiNPs) have emerged as multifunctional tools in sustainable agriculture, demonstrating significant efficacy in promoting crop growth and enhancing plant resilience against diverse biotic and abiotic stresses. Although their ability to strengthen antioxidant defense systems and activate systemic immune responses is well documented, the fundamental mechanisms driving these benefits remain unclear. This review synthesizes emerging evidence to propose an innovative paradigm: SiNPs remodel plant redox signaling networks and stress adaptation mechanisms by forming protein coronas through apoplastic protein adsorption. We hypothesize that extracellular SiNPs may elevate apoplastic reactive oxygen species (ROS) levels by adsorbing and inhibiting antioxidant enzymes, thereby enhancing intracellular redox buffering capacity and activating salicylic acid (SA)-dependent defense pathways. Conversely, smaller SiNPs infiltrating symplastic compartments risk oxidative damage due to direct suppression of cytoplasmic antioxidant systems. Additionally, SiNPs may indirectly influence heavy metal transporter activity through redox state regulation and broadly modulate plant physiological functions via transcription factor regulatory networks. Critical knowledge gaps persist regarding the dynamic composition of protein coronas under varying environmental conditions and their transgenerational impacts. By integrating existing mechanisms of SiNPs, this review provides insights and potential strategies for developing novel agrochemicals and stress-resistant crops. Full article

Prenylation increases the structural diversity and biological activity of flavonoids. In this study, an aromatic prenyltransferase, FgPT1, was identified from Fusarium globosum. This enzyme was demonstrated to specifically catalyze the prenylation of flavanones, including naringenin, hesperitin, eriodictyol, liquiritigenin, rac-pinocembrin, and dihydrogenistein, and exhibited no activity toward other types of flavonoids, including chalcones, flavonols, isoflavonoids, and flavonols. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and nuclear magnetic resonance (NMR) analysis indicated that the majority of prenylated products were 6-C prenyl flavanones, with the exception of liquiritigenin, which was additionally transformed to 4′-O prenyl liquiritigenin. Enzyme kinetic analysis suggested that FgPT1 exhibited the highest catalytic efficiency towards naringenin, with a k_cat/K_M value determined as 61.92 s⁻¹ M⁻¹, and the lowest catalytic efficiency towards liquiritigenin, with a k_cat/K_M of 1.18 s⁻¹ M⁻¹. Biochemical characterization suggested that FgPT1 functioned as a metal-dependent enzyme with optimal activity in the presence of Ba²⁺ at pH 7.5 and 30 °C. Site-directed mutagenesis resulted in a series of mutants, including A325V with impaired prenylation activity and V116I, V181I, and V194I with enhanced activity. V194I displayed the highest enzymatic activity with a nine-fold increase compared to wild-type FgPT1. Full article

Through soil incubation experiments, the effects of aged PBAT + PLA (polybutylene adipate terephthalate + polylactic acid) film fragments were analyzed. Surface characteristics and chemical structures of the films changed significantly after one (T2) and two years (T1) of aging compared to new films (T3). Both new and aged fragments reduced soil pH, altered enzyme activities, and influenced dissolved organic matter (DOM) fluorescence. Alkaline phosphatase activity declined by 33.2%, 23.8%, and 11.6% for T1, T2, and T3, respectively, while urease and sucrase activities increased in a time-dependent manner. The degree of soil humification rose by 66.4%, 60.4%, 49.3%, and 88.6% for T1, T2, T3, and T4, respectively, compared to the control (CK). Aged films exhibited stronger DOM fluorescence intensity than new films. Tessier extraction analysis revealed a decrease in exchangeable Cd by 22.9%, 13.1%, and 10.2% for T1, T2, and T3, respectively, while organically bound Cu increased. Correlation analysis indicated a significant positive relationship between soil humification and heavy metal bioavailability. These findings provide insight into the ecological effects of biodegradable agricultural films, offering a theoretical foundation for assessing their environmental risks and safety. Full article

Despite the many current cholesterol-lowering drugs on the market, the persistent surge of hypercholesterolemic-related complications ignites a fascinating search for the discovery of novel therapeutics. This study aimed at investigating the anti-hypercholesterolemic effect of Bauhinia bowkeri extracts. The plant material was sequentially extracted with n-hexane, dichloromethane (DCM), and 70% ethanol. The phytochemical constituents of the extracts were analyzed through GC-MS and the antioxidant activity of the extracts was screened against a wide range of free radicals (ABTS, DPPH, hydroxyl radical, and nitric oxide). The extracts were also screened for the metal iron chelating and reducing power potential. The enzyme inhibitory activity of the extracts on pancreatic lipase, cholesterol esterase, and HMG-CoA reductase as well as the bile acid binding capacity were evaluated. Among the total of 122 compounds detected in the three extracts, only 7 compounds (E-15-Heptadecenal, Diethyl Phthalate, 9,12,15-Octadecatrienoic acid ethyl ester, (Z,Z) Tetradecane 5-methyl, and Octadecane 5-methyl) were found to be common in all the extracts. The extract displayed a varying degree of efficiency on free radicals with IC₅₀ values ranging from 0.07 mg/mL to 0.41 mg/mL. A concentration-dependent inhibition of pancreatic lipase and cholesterol esterase activities, along with a reduction in the bile-binding capacity exhibited by the extracts, was noted. In silico investigations of some of the phytoconstituent revealed significant inhibition of HMG-CoA reductase, cyclooxygenase, and hormone-sensitive lipase with a binding affinity that ranged between −5.1 and −7.0 kcal/mol. These findings suggest that Bauhinia bowkeri extracts possess potential antioxidant and anti-hypercholesterolemic properties. Full article

Iron-based metal–organic frameworks (Fe-MOFs) are widely used for agricultural chemical delivery due to their high loading capacity, and they also have the potential to provide essential iron for plant growth. Therefore, they hold significant promise for agricultural applications. Evaluating the plant biotoxicity of Fe-MOFs is crucial for optimizing their use in agriculture. In this study, we used the natural biomacromolecule carboxymethyl cellulose (CMC) to encapsulate the Fe-MOF NH₂-MIL-101 (Fe) (MIL). Through hydroponic experiments, we investigated the biotoxic effects of Fe-MOFs on rice before and after CMC modification. The results show that the accumulation of iron in rice is dependent on the dose and the exposure concentration of Fe-MOFs. CMC modification (MIL@CMC) can reduce the release rate of Fe ions from Fe-MOFs in aqueous solutions with different pH values (5 and 7). Furthermore, MIL@CMC treatment significantly increases the absorption of iron by both the aboveground and root parts of rice. MIL@CMC significantly alleviated the growth inhibition of rice seedlings and increased the aboveground biomass of rice under medium- to high-exposure conditions. Specifically, in rice roots, MIL induced a more intense oxidative stress response, with significant increases in the activities of related antioxidant enzymes (CAT, POD, and SOD) and MDA content. Our results demonstrated that the encapsulation of NH₂-MIL-101(Fe) using CMC effectively alleviated oxidative damage and promoted the uptake and growth of iron in rice. These findings suggest that rational modification can have a positive effect on reducing the potential phytotoxicity of MOFs and improving their biosafety in agricultural applications. Full article

Proteus mirabilis has been identified as the third most frequent reason for catheter-associated urinary tract infections. The production of urease significantly enhances the force of catheter blockage caused by biofilm formation. Because biofilms are important virulence factors that make antibiotics less potent, it is becoming increasingly important to develop novel alternative antibiotics. In addition to the unique properties they possess, nanoparticles made from metal oxide are currently attracting considerable attention as possible antibacterials. This research aims to explore the potential anti-biofilm properties of green manufactured ZnO-CuO nanoparticles generated by P. mirabilis. By synthesizing reductive enzymes, bacterial cells can participate in the biosynthesis process. This study explores whether green synthesized ZnO-CuO nanoparticles can work as an anti-biofilm agent formed by P. mirabilis. These nanoparticles were generated using Bacteriocins to determine their effectiveness against bacteria, which were partially purified and showed antimicrobial activity against Gram-negative bacteria of P. mirabilis. AFM, TEM, FESEM, XRD, and ultraviolet (UV)–visible spectroscopy were used to analyze the biosynthesized nanoparticles to ascertain their chemical and physical characteristics. XRD verified the hexagonal structure, TEM demonstrated a size range of 96.00 nm, and FESEM verified the surface morphology. The dispersion and roughness of the nanoparticles are shown through AFM examination. The produced nanoparticles’ UV-visible spectra displayed a maximum peak at 287 and 232 nm. When applied to strains (wild-type) of Proteus mirabilis (multidrug-resistant), copper and zinc nanoparticles had notable biofilm inhibitory effects. Weak biofilm production has been demonstrated by bacteria that effectively generate biofilms, following incubation with 128 μg/mL subminimum inhibitory concentrations (MICs) of CuO nanoparticles for 24 and 48 h at 37 °C. Following treatment with the ZnO-CuO nanocomposite of these strains, downregulation alterations in LuxS expression were detected by utilizing a real-time PCR process. After this, isolates were treated with the nanocomposite, and downregulated shifts in LuxS expression were found by utilizing the real-time PCR technique in contrast with the isolates that were not treated. Zinc oxide (ZnO) nanoparticles can be utilized as antibacterial agents in a concentration-dependent manner, aligning with all observed findings. The present research demonstrates that green synthesized copper oxide–zinc oxide nanocomposites are effective anti-biofilm agents against P. mirabilis. Their noteworthy downregulation of LuxS gene expression successfully prevents biofilm formation and swarming motility. Full article

Biosensing shows promise in detecting cancer, renal disease, and other illnesses. Depending on their transducing processes, varieties of biosensors can be divided into electrochemical, optical, piezoelectric, and thermal biosensors. Advancements in material production techniques, enzyme/protein designing, and immobilization/conjugation approaches can yield novel nanoparticles with further developed functionality. Research in cutting-edge biosensing with multifunctional nanomaterials, and the advancement of practical biochip plans utilizing nano-based sensing material, are of current interest. The miniaturization of electronic devices has enabled the growth of ultracompact, compassionate, rapid, and low-cost sensing technologies. Some sensors can recognize analytes at the molecule, particle, and single biological cell levels. Nanomaterial-based sensors, which can be used for biosensing quickly and precisely, can replace toxic materials in real-time diagnostics. Many metal-based NPs and nanocomposites are favorable for biosensing. Through direct and indirect labeling, metal-oxide NPs are extensively employed in detecting metabolic disorders, such as cancer, diabetes, and kidney-disease biomarkers based on electrochemical, optical, and magnetic readouts. The present review focused on recent developments across multiple biosensing modalities using metal/metal-oxide-based NPs; in particular, we highlighted the specific advancements of biosensing of key nanomaterials like ZnO, CeO₂, and TiO₂ and their applications in disease diagnostics and environmental monitoring. For example, ZnO-based biosensors recognize uric acid, glucose, cholesterol, dopamine, and DNA; TiO₂ is utilized for SARS-CoV-19; and CeO₂ for glucose detection. Full article

Cadmium (Cd) is a pervasive heavy metal pollutant released into the environment through industrial activities such as mining, smelting, and agricultural runoff. This study aimed to investigate the molecular and metabolic impacts of Cd exposure on the silk glands of Trichonephila clavata, a species renowned for producing silk with exceptional mechanical properties. Cd accumulation in spider bodies and silk glands was significantly higher in the low- and high-Cd groups compared to controls, with a dose- and time-dependent increase. Oxidative stress markers, including superoxide dismutase, glutathione peroxidase, peroxidase, and malondialdehyde, were significantly elevated, indicating a robust stress response. Proteomic analysis identified 2498 proteins, with 227 differentially expressed between Cd-treated and control groups. Key metabolic pathways, including glutathione metabolism, cysteine and methionine metabolism, and amino acid biosynthesis, were significantly disrupted. Downregulation of enzymes such as glutathione synthase and S-adenosylmethionine synthetase highlighted oxidative imbalance and impaired sulfur metabolism, indicating disruptions in redox homeostasis and energy metabolism critical for silk production. These findings demonstrate that Cd exposure alters oxidative stress responses, disrupts key metabolic pathways, and impairs silk gland functionality at multiple molecular levels. This study advances the understanding of the impact of heavy metal stress on spider physiology and provides a foundation for further research on the ecological implications of Cd contamination. Full article

Alkaline phosphatase (ALP) of the PhoA family is an important enzyme in mammals, microalgae, and certain marine bacteria. It plays a crucial role in the dephosphorylation of lipopolysaccharides (LPS) and nucleotides, which overstimulate cell signaling pathways and cause tissue inflammation in animals and humans. Insufficient ALP activity and expression levels have been linked to various disorders. This study aims to produce recombinant ALP from the marine bacterium Cobetia amphilecti KMM 296 (CmAP) in transformed leaves and calli of Nicotiana tabacum and to elucidate the influence of the plant host on its physical and chemical properties. N. tabacum has proven to be versatile and is extensively used as a heterologous host in molecular farming. The alp gene encoding for CmAP was cloned into the binary vectors pEff and pHREAC and transformed into N. tabacum leaves through agroinfiltration and the leaf disc method for callus induction using Agrobacterium tumefaciens strain EHA105. Transformed plants were screened for recombinant CmAP (rCmAP) production by its enzymatic activity and protein electrophoresis, corresponding to 55 kDa of mature CmAP. A higher rCmAP activity (14.6 U/mg) was detected in a homogenate of leaves bearing the pEFF-CmAP construct, which was further purified 150-fold using metal affinity, followed by anion exchange chromatography. Enzymatic activity and stability were assessed at different temperatures (15–75 °C) and exposure times (≤1 h), with different buffers, pHs, divalent metal ions, and salt concentrations. The results show that rCmAP is relatively thermostable, retaining its activity at 15–45 °C for up to 1 h. Its activity is highest in Tris HCl (pH 9.0–11.0) at 35 °C for 40 min. rCmAP shows higher salt-tolerance and divalent metal-dependence than obtained in Escherichia coli. This can be further explored for cost-effective and massively scalable production of LPS-free CmAP for possible biomedical and agricultural applications. Full article

Pacific white shrimp shell protein hydrolysates (SSPHs) produced using alcalase (UAH) and papain (UPH), and polyphenols (PPNs) conjugates were prepared using variable concentrations (0.5–3% w/v) of different polyphenols (EGCG, catechin, and gallic acid). When 2% (v/v) of a redox pair was used for conjugation, 0.5% (w/v) of PPNs resulted in the highest conjugation efficiency (CE), regardless of the polyphenol types. However, CE decreased further with increasing levels of PPNs (p < 0.05). SSPHs at 2% retained the highest CE when combined with the selected PPN and redox pair concentrations (p < 0.05). FTIR and ¹H-NMR analysis confirmed the successful conjugation of PPNs with the SSPHs. Among all the conjugates, EGCG conjugated with UAH (A–E) or UPH (P–E) exhibited the highest DPPH/ABTS radical scavenging, and metal chelating activities, respectively. The highest FRAP activity was noticed for A–E conjugate followed by UAH-catechin (A–C) and UPH-catechin (P–C) conjugates. The A–C sample (6 mg/mL) demonstrated the strongest inhibition efficiency against α-amylase, α-glucosidase, and pancreatic lipase (89.29, 81.23, and 80.69%, respectively) than other conjugates (p < 0.05). When A–C conjugate was added into surimi gels prepared from Indian mackerel (IM) and threadfin bream (TH) mince at various levels (2–6%; w/w), gel strength, and water holding capacity was increased in a dose-dependent manner, regardless of surimi type. However, whiteness decreased with increasing A–C levels. After the in vitro digestion of surimi gels, antioxidant and enzyme inhibitory activities were also increased as compared to the digest prepared from control surimi gels (added without A–C conjugate). Thus, waste from the shrimp industry in conjugation with plant polyphenols could be utilized to produce antioxidant and antidiabetic or anti-obesity agents, which could be explored as a promising additive in functional foods and nutraceuticals. Full article