Search Results (1,003)

Background: Metabolic enzymes catalyze biochemical pathways that sustain cellular metabolism. Their activity, stability, and molecular interactions are extensively regulated by post-translational modifications (PTMs). However, an integrated systems-level understanding of how diverse PTMs are organized across the human metabolic network remains poorly defined. Methods: We integrated experimentally reported PTM annotations from PhosphoSitePlus, dbPTM, and the quantitative PTM database (qPTM), and identified 29 distinct PTM types present across the 771 human metabolic enzymes. PTM features were quantitatively characterized at multiple levels, including sequence- and composition-based metrics (modification density and PTM potentiality rate), recurrence- and co-occurrence-based features (predominant sites, hotspot regions and PTM crosstalk), and functional-context annotations (protein-region localization and mutation overlap). These integrated features were subsequently used for unsupervised clustering to evaluate higher-order organizational patterns. Results: The analysis revealed that PTMs are unevenly distributed across metabolic enzymes, with phosphorylation, acetylation, ubiquitination, and methylation representing the most prevalent and recurrent regulatory modifications. Clustering segregated enzymes into two regulatory groups: (i) a PTM-enriched regulatory group characterized by high PTM density, frequent hotspot and crosstalk regions, and enrichment of rate-limiting enzymes, and (ii) a broad metabolic group with comparatively sparse PTM regulation. This non-uniform organization reflects the preferential accumulation of multiple regulatory PTMs on enzymes occupying key control points in central metabolic pathways, thereby forming a discrete regulatory subnetwork within metabolism. Conclusions: This study presents a systems-level, multi-PTM atlas of human metabolic enzymes and provides a quantitative framework for prioritizing PTM-regulated enzymes and pathways relevant to signaling–metabolism integration and disease-associated metabolic regulation. Full article

Phosphofructokinase 1 (PfkA) mediates the ATP-dependent phosphorylation of fructose-6-phosphate and is a key, controlling enzyme in glycolysis for Escherichia coli and other organisms. In this study, 22 chromosomally expressed PfkA variants were constructed in E. coli C. These variants, the wild-type strain, and the ∆pfkA strain were compared for growth rates using glucose as the sole carbon source. The majority of variants (14 of 22) attained a growth rate less than 20% of the growth rate of the wild-type strain (0.94 h⁻¹) and thus similar to the knockout strain (0.12 h⁻¹). Three variants (R171S, F76Y, and R77A), representing a range of growth phenotypes, and strains expressing the wild-type PfkA and the ∆pfkA deletion strain were additionally examined for key intracellular metabolites and gene expression under nitrogen-limited steady-state conditions. These five strains could be distinguished by two groupings: strains with relatively high growth rates under batch conditions (wild-type and R77A variant) showed the greatest glucose consumption rate and formed acetate, whereas strains with low growth rates (F76Y, R77A, and ∆pfkA) exhibited low glucose consumption and did not accumulate acetate. As the PfkA mutation severity increased, the intracellular concentrations of acetyl-CoA and fructose-1,6-bisphosphate and the sum of dihydroxyacetone and glyceraldehyde-3-phosphate greatly decreased. Although the mutation severity had a limited effect on the expression of maeB and icd genes expressing malic enzyme and isocitrate dehydrogenase, it correlated with reduced expression of zwf and pta genes expressing glucose-6P-dehydrogenase and phosphotransacetylase, respectively. The results highlight the great sensitivity of the enzyme to substitutions and the key role it plays in controlling glycolytic flux. Full article

The milk metabolite profiles of dairy cows during the dry-off and peripartum periods were investigated using ¹H NMR combined with chemometric analysis to evaluate the effects of different dry-off management strategies. Milk samples were collected 14 days before dry-off (T0) and 28 days after calving (T1) from cows receiving an internal teat sealant combined with intramammary antibiotics (CTR), an internal teat sealant alone (SIG), or an internal teat sealant associated with dietary supplementation of lyophilized Aloe arborescens (ASIG). Analysis of both aqueous and organic milk extracts revealed no significant metabolite differences among treatment groups. In contrast, a clear discrimination was detected between samples collected at T0 and T1. Aqueous extracts at T0 were characterized by higher levels of choline, butyrate, branched-chain amino acids, and N-acetylated compounds, whereas T1 samples exhibited higher levels of saccharides, citrate, phosphorylcholine, and galactose-1-phosphate. Organic extracts at T0 showed higher concentrations of conjugated linoleic acids (CLAs) and caproleic acid. These findings indicated that the physiological stage of the cows had a more pronounced impact on milk metabolite composition than the dry-off treatments, with no detrimental effects on milk composition or overall metabolite balance. Full article

Proanthocyanidins (PACs) are a key group of bioactive phytochemicals known to provide health benefits. Most PACs are non-bioavailable polymeric molecules that need to be biotransformed by colonic microbes into simple metabolites to exert their pharmacological effects. In this study, six previously unexamined PAC metabolites from Saccharomyces cerevisiae, 3-aminophenol (3-AMP), 3-aminosalicylic acid, 2,4-dihydroxy-6-methylbenzaldehyde, 4-hydroxyphenylacetamide (4-HPA), 3-phenyllactic acid, and 2,4,6-trihydroxyacetophenone, were tested for their antiadipogenic activity using an insulin-dependent 3T3-L1 preadipocyte differentiation model. Lipid accumulation in differentiating preadipocytes was visualized and measured with the Oil Red O assay. Only 3-AMP and 4-HPA significantly reduced lipid accumulation at a concentration of 25 µM. To understand the cellular mechanisms, protein levels of key regulators of adipogenesis and lipid metabolism were analyzed using Western blotting. 3-AMP and 4-HPA may attenuate lipid accumulation by suppressing de novo lipogenesis, with 3-AMP downregulating the peroxisome proliferator-activated receptor (PPAR)-γ/acetyl-CoA carboxylase (ACC)/fatty acid synthase (FAS) axis and 4-HPA primarily inhibiting ACC/FAS signaling. Molecular docking studies indicated that 3-AMP may downregulate PPAR-γ expression through competitive inhibition of insulin receptors. These preliminary findings suggest that 3-AMP and 4-HPA exhibit potential antiadipogenic effects, highlighting PAC-derived postbiotics as promising nutraceuticals for mitigating obesity risk. Full article

This study addresses the thermodynamic aspects of galactose oxidase (GAOx) adsorption and redox behavior on gold electrodes modified with self-assembled monolayers (SAMs) derived from thiocarboxylic acids, namely N-acetyl-L-cysteine (NAC), mercaptosuccinic acid (MSA), mercaptoacetic acid (MAA), and L-cysteine (Cys). The electrochemical response of GAOx immobilized on these SAM-modified surfaces was analyzed to extract key thermodynamic parameters governing enzyme–electrode interactions, including the formal redox potential (E°), surface excess (Γ), potential of zero charge (E_zc), adsorption free energy (∆G_add), differential capacitance (C_dl), and surface tension (γ). The results demonstrate that the nature of the terminal functional group of the SAM significantly influences the thermodynamic stabilization of GAOx at the gold interface. Shifts in the redox potential are attributed to specific coordination and electrostatic interactions between the SAM functional groups and the GAOx metal center, leading to distinct interfacial energy landscapes. Overall, the SAM-modified electrodes provide a well-defined thermodynamic framework to probe enzyme orientation, interfacial charge distribution, and stabilization of the redox-active state of GAOx during direct electron transfer. These results offer guidelines based on thermodynamic and kinetic principles for customizing enzyme–electrode interfaces, which can enhance the efficiency, stability, and consistency of third-generation electrochemical biosensors. Full article

Dendrobium officinale (DO) is a traditional medicinal and edible plant whose polysaccharides help modulate gastrointestinal and metabolic functions. Fresh DO is commonly processed into “Fengdou” to prolong shelf life, but the effects of this processing on polysaccharide structure and bioactivity remain unclear. In this study, polysaccharides from fresh DO (FDOP) and Fengdou (DDOP) were isolated, purified, and comparatively characterized. Based on structural analyses, FDOP and DDOP have similar functional groups and O-acetylated pyranosyl structures in both polysaccharides, which are identified as mannose–glucose heteropolysaccharides. However, FDOP was characterized by a higher mannose-to-glucose ratio (79.77:19.57) and molecular weight (187.1 kDa), as well as a more structurally diversified →4-linked backbone. In contrast, DDOP contained more glucose (68.74:30.94) and exhibited a lower molecular weight (125.1 kDa) and simplified backbone. In zebrafish models, both polysaccharides were found to alleviate loperamide-induced constipation and reduce lipid accumulation. DDOP showed stronger constipation-relieving activity, whereas FDOP exerted more pronounced hypolipidaemic effects, which can be ascribed to the higher molecular weight, mannose enrichment, and more complex backbone structure. These findings provide a structural basis and theoretical support for developing DO-derived polysaccharides as functional food ingredients targeting constipation and dyslipidaemia. Full article

The title compound 2-iodopyridin-3-yl acetate was obtained by acetylation of the OH group of 2-iodo-3-hydroxypyridine. Knowing that the hydroxyl group, as a strong H-bond donor in halogenated hydroxypyridines, usually directs supramolecular packing and might enforce possible halogen–halogen contacts, we crystallized 2-iodo-3-acetoxypyridine with the aim of disrupting the most important H-bond donor and assessing the propensity of the iodine for halogen bond formation. Indeed, in the compound 2-iodopyridin-3-yl acetate, the crystal packing is characterized by infinite 3D chains bonded through I···O=C and C-H···I contacts between adjacent molecules. These chains are interconnected by weak C-H···O contacts, implying the presence of oxygen in the ester. The I···H contact with the C-H axis perpendicular to the electron belt of the iodine atom can enhance the σ-hole of the iodine and act cooperatively in crystal cohesion. No halogen–halogen contacts were present. Full article

Zearalenone (ZEA) is a common estrogenic mycotoxin in rabbit breeding that causes various toxic effects. Selenomethionine (SeMet) is a feed additive with potent anti-inflammatory and antioxidant properties. To evaluate the protective role and action mechanism of SeMet against ZEA-induced liver injury, 90-day-old rabbits were randomized into five groups: control, ZEA-alone, and SeMet pretreatment at 0.2, 0.35, and 0.5 mg/kg. SeMet was administered for 21 days, followed by continuous intragastric ZEA (1.2 mg/kg B.W.) for 7 days starting on day 15. As a result, ZEA exposure significantly elevated liver function parameters, disrupted lobular architecture, and impaired glycogen synthesis. It also induced liver oxidative stress, thus upregulating expressions of Bax, Cyt C, Caspase-3, and Caspase-9, triggering hepatocyte apoptosis, mitochondrial damage, and mitophagy. SeMet pretreatment activated SIRT1, reduced the acetylated FOXO1/P53 levels, and enhanced CAT and SOD2 expression, mitigating ZEA-induced oxidative stress, apoptosis, and mitophagy. Based on the above findings, SeMet’s alleviating effect might be mediated via the SIRT1-FOXO1/P53 pathway, with 0.35 mg/kg of SeMet exerting the optimal efficacy, highlighting its therapeutic potential for mitigating ZEA-induced hepatotoxicity in rabbits. Full article

The environmental threat posed by small, single-use sachets sourced from 48% annual waste from excessive packaging has been assessed by investigating the development of nano-incorporated bioplastic films from the high-yield plant, maguey (Agave cantala). Maguey cellulose was acetylated (using 10 and 15 mL of acetic anhydride for 16, 24, and 32 h), successfully yielding a high of 81.34% maguey cellulose acetate (MCA). MCA was confirmed to contain acetate groups (C=O, C-H, C-O) via FT-IR and exhibited a hydrophobicity of a 121.897° contact angle. Bioplastic films were fabricated using MCA solution combined with 15% (w/w) commercial cellulose acetate (CCA)/MCA and reinforced with nanoclay (NC) at 0.5%, 1%, and 3% (w/w) concentrations. Nanomaterial incorporation generally improved properties; however, mechanical strength declined with increasing NC concentration, recording tensile strengths of 2.01 MPa, 0.89 MPa, and 0.78 MPa for the 0.5%, 1%, and 3% NC films, respectively. Conversely, the 3% NC film showed the best barrier property, with a water vapor transmission rate (WVTR) of 31.14 g/m² h. Surface morphology confirmed NC integration (nanomaterial sizes 29.74 nm to 107.3 nm), and the 0.5% NC film displayed the smooth structure ideal for sustainable packaging. The slight increase in contact angle observed between the 0% NC (60.768°) and 0.5 NC (62.904°) films suggested limitations in NC dispersion. Overall, the findings demonstrate the potential of using regenerated maguey cellulose acetate to create nano-bioplastic films with tailored mechanical and barrier properties for sustainable packaging, though optimization of NC loading and dispersion is necessary to maximize strength. Full article

In order to improve the utilization of alkali lignin (AL) as an effective component for ultraviolet (UV) shielding, demethylation and acetylation modification were carried out to improve the UV absorption performance of lignin. Then, lignin-based sunscreens were successfully prepared by mixing the modified lignin and commercial cream without UV shielding ingredients. The modified alkali lignin was comprehensively characterized in terms of its molecular weight, functional groups and structural properties by GPC, UV spectroscopy and ³¹P NMR. The results showed that the Mw of all three lignin feedstocks (AL, AL_MeOH and AL_Acetone) was decreased with prolonged demethylation time. Compared to the original feedstock, demethylated AL had a darker color and improved UV absorption performance due to the increased phenolic hydroxyl content (approximately 4.35 mmol/g). ³¹P-NMR spectra showed that the guaiacyl phenolic hydroxyl content decreased rapidly after acetylation, causing the sample color to become lighter. Among all lignin-based sunscreens, DAL_Acetone achieved the highest SPF value of 11.23, a 69.4% increase over its pre-reaction level and a 7.58-fold enhancement compared to the original lignin. In summary, this study opens a promising avenue for repurposing industrial lignin as a sustainable biomaterial in high-value sectors like UV-blocking agents and cosmetic formulations. Full article

Acetyl phosphate (AcP) is a microbial metabolite acting as a link between cell metabolism and signaling, providing the survival of bacteria in the host. AcP was also identified as an intermediate of pyruvate oxidation in mammalian mitochondria and was found in the human blood in some severe pathologies. The possible contribution of circulating AcP to the maintenance of the physiological or pathological states of the body has not been studied. Since AcP can function as a donor of phosphate groups, we have examined in vitro the influence of AcP on calcium signaling in mitochondria and cells by measuring the membrane potential and the calcium retention capacity of mitochondria by selective electrodes and by assaying the cell calcium signaling by Fura-2AM fluorescent radiometry. AcP was shown to induce a concentration-dependent increase in the mitochondrial resistance to calcium ion loading both in the control and in the presence of ADP. This effect was especially pronounced when mitochondria were incubated in a phosphate-free medium; under these conditions, AcP strongly raised the membrane potential and increased the rate of calcium uptake and the calcium retention capacity several times. Moreover, AcP induced similar changes in human cells when calcium signaling was activated by ATP, to a greater extent in neuroblastoma cells than in astrocytes. In the presence of AcP, a tendency for an increase in the amplitude and a decrease in the continuance of the ATP-induced calcium response was observed. These changes are probably associated with the activation of calcium buffering by mitochondria due to the delivery of phosphate during the hydrolysis of AcP. The results show that AcP is involved in the regulation of the Ca²⁺ balance in cells by activating the accumulation of calcium ions by mitochondria, especially under phosphate deficiency. A shift in calcium signaling mediated by AcP supplementation may be caused by hyperphosphatemia, which is now considered as one of basic contributors to cellular dysfunction and progression of various diseases, including sepsis. Full article

The objective of this study was to investigate the effects of replacing fishmeal with H. illucens larval meal on the colonic immune homeostasis in weaned piglets in enterotoxigenic Escherichia coli (ETEC)-challenged pig housing. Seventy-two weaned piglets, aged 28 days, were randomly divided into three groups for dietary treatment: the basal diet (negative control, NC), the positive control diet (PC) supplemented with 1445 mg zinc/kg zinc oxide in the basal diet, and the H. illucens larval meal complete replacement of fishmeal in the basal diet (HILM), for 28 days in ETEC-challenged pig housing. The results showed that the relative transcript abundances of ZO-1, pBD2, PR39, and PG1–5 were increased (p < 0.05) in pigs fed the HILM diet compared with those fed the NC diet. In addition, the HILM diet reduced (p < 0.05) the serum contents of IL-8 and increased (p < 0.05) the serum contents of IL-10 and IgG compared with the NC diet. In terms of the molecular mechanisms by which immune homeostasis is improved, the p-NF-κB/ NF-κB ratio and TLR2 protein expression in the colon were decreased (p < 0.05) in pigs fed the HILM diet compared with those fed the NC diet. Compared with the NC diet, the HILM diet reduced (p < 0.05) the protein expression of HDAC3 and HDAC7 in the colon of pigs. The SIRT1, acH3K9, and pH3S10 protein expressions in the colon were the greatest (p < 0.05) in pigs fed the HILM diet compared with the NC diet. HILM diets improved the colonic immune homeostasis in weaned piglets by enhancing the antimicrobial peptide expression, thereby mitigating ETEC challenges in pig housing. Mechanistically, HILM diets promote antimicrobial peptide expression through increased histone acetylation (acH3K9 and pH3S10). Full article

Improving the hydrophilicity and tissue adhesion of polymers remains a significant challenge in tissue engineering and is often addressed by introducing functional groups that enhance polymer–tissue interactions. In this field, L-cysteine (Cys) and N-acetyl-L-cysteine (NAC) are particularly interesting due to their functional carboxyl and amine groups, which are prone to hydrogen bonding. Following this trend, this study (i) investigated the feasibility of grafting Cys or NAC onto the linear oligoitaconates via thio-Michael addition and (ii) examined the influence of amino acid incorporation on the material’s physicochemical properties. NMR-based calculations confirmed nearly 100% addition efficiency for Cys and a slightly lower, but still high, efficiency for NAC. FT-IR spectra confirmed thiol-based addition, as signal from the Cys/NAC S–H stretching vibrations was not observed in the adduct’s spectra. The obtained adducts showed thermal stability up to 200 °C and glass transition temperatures below −20 °C. They were soluble in common organic solvents, except for Cys adducts with oligo(propylene itaconate) and oligo(hexylene itaconate), which were water-soluble only. Due to the low molecular weight (below 1000 g/mol) of oligoitaconates, their adducts cannot serve as standalone scaffold components. However, they showed potential for use as modifiers for high-molecular-weight polylactide or poly(ɛ-caprolactone)-based scaffolds. Full article

Background/Objectives: The delayed effects of organophosphate poisoning may manifest years after exposure, often masked by age-related diseases. The aim of this retrospective cohort study was to identify the biochemical “trace” that could remain in patients decades after poisoning. We determined a wide range of biochemical parameters, along with the spectrum of esterified and non-esterified fatty acids (EFAs and NEFAs, respectively), in the blood plasma of a cohort of elderly patients diagnosed with occupational pathology (OP) due to (sub)chronic exposure to organophosphates in the 1980s. Methods: Elderly patients with and without a history of exposure to organophosphates were retrospectively divided into two groups: controls (n = 59, aged 73 ± 4, men 29% and women 71%) and those with OP (n = 84, aged 74 ± 4, men 29% and women 71%). The period of neurological examination and blood sampling for subsequent analysis was from mid-2022 to the end of 2023. Determination of the content of biomarkers of metabolic syndrome, NEFAs, and EFAs in blood plasma was performed by HPLC-MS/MS and GC-MS. Results: The medical histories of the examined elderly individuals with OP and the aged control group included common age-related diseases. However, patients with OP more often had hepatitis, gastrointestinal diseases, polyneuropathy, and an increased BMI. Analysis of metabolic biomarkers revealed, in the OP group, a decrease in the concentrations of 3-hydroxybutyrate (p < 0.05), 2-hydroxybutyrate (p < 0.0001), and acetyl-L-carnitine (p < 0.001) and the activity of butyrylcholinesterase (BChE) (p < 0.05), but an increase in the esterase activity of albumin (p < 0.05). Correlation analysis revealed significant relationships between albumin esterase activity and arachidonic acid concentrations in the OP group (0.64, p < 0.0001). A study of a wide range of fatty acids in patients with OP revealed reciprocal relationships between EFAs and NEFAs. A statistically significant decrease in concentration was shown for esters of margaric, stearic, eicosadienoic, eicosatrienoic, arachidonic, eicosapentaenoic, and docosahexaenoic fatty acids. A statistically significant increase in concentration was shown for non-esterified heptadecenoic, eicosapentaenoic, eicosatrienoic, docosahexaenoic, γ-linolenic, myristic, eicosenoic, arachidonic, eicosadienoic, oleic, linoleic, palmitic, linoelaidic, stearic, palmitoleic, pentadecanoic, and margaric acids. Decreases in the ratios of omega-3 to other unsaturated fatty acids were observed only for the esterified forms. Conclusions: The data obtained allow us to consider an increased level of NEFAs as one of the main cytotoxic factors for the vascular endothelium. Modification of albumin properties and decreased bioavailability of docosahexaenoic acid could be molecular links that cause specific manifestations of organophosphate-induced pathology at late stages after exposure. Full article

Background/Objectives: The safety of intraperitoneal mesh placement in contaminated fields remains controversial because of the increased risk of inflammation and adhesion formation. N-acetyl-L-cysteine (NAC) has antioxidant, pro-fibrinolytic and antibiofilm actions that could attenuate this response. The aim of this study is to determine whether NAC reduces mesh-related inflammation in a septic model created by intraperitoneal Escherichia coli (E.coli) inoculation. The primary comparison was prospectively defined between E. coli–inoculated animals treated with NAC (D) and those without NAC (B). Groups without E. coli (A,C,E) are presented for context and were compared previously. Methods: In this randomized, double-blind experimental model (five groups, n = 20 per group), all rats underwent midline laparotomy with intraperitoneal placement of a composite mesh, followed by standardized ciprofloxacin administration. The septic groups received intraperitoneal E. coli, while the NAC-treated groups additionally received intraperitoneal NAC (150 mg/kg). Serum levels of IL-1α, IL-6, and TNF-α were measured on postoperative days 7, 14, and 21. On day 21, adhesions were graded using the Modified Diamond system, histology (inflammatory infiltration, fibrosis, neovascularization) was scored, and mesh cultures were obtained. Cytokine data were analyzed with repeated-measures ANOVA, while categorical or ordinal outcomes were assessed using χ² or Fisher’s exact tests with Bonferroni-adjusted pairwise comparisons. Results: E. coli inoculation significantly increased adhesion burden and worsened histologic scores compared with controls (both p < 0.001). NAC administration in the septic model significantly reduced adhesions and improved all histologic domains relative to E. coli alone (all p ≤ 0.003), with values comparable to controls (non-significant across domains). For cytokines, there was a significant overall group effect for IL-1α, IL-6, and TNF-α (all p < 0.001), without a main effect of time or time × group interaction. Pairwise contrasts showed lower IL-1α (p = 0.024), IL-6 (p < 0.001), and TNF-α (p < 0.001) levels in group D versus B, and lower IL-6 and TNF-α in group D versus A (both p < 0.001). Mesh culture positivity rate was higher in group B than A (p < 0.001) and showed a non-significant reduction in group D versus B (p = 0.10). No perioperative deaths occurred. Conclusions: NAC attenuated septic, mesh-associated inflammation—normalizing adhesions and histology and reducing IL-6 and TNF-α— supporting its role as a host-directed adjunct alongside antibiotics. Further translational studies are warranted to define the optimal dose, timing, and clinical indications. Full article