Inhibited Enzyme Activity Research Articles

Novel 5-Fluorouracil analogues versus perfluorophenyl ureas as potent anti-breast cancer agents: Design, robust synthesis, in vitro, molecular docking, pharmacokinetics ADMET analysis and dynamic simulations

To investigate the therapeutic potential of 5-Fluorouracil-based analogues, a straightforward synthetic technique was employed to synthesize a novel series of 5-arylurea uracil derivatives (AUFU01-03) and aryl-urea derivatives bearing perfluorophenyl (AUPF01-03). Reliable tools such as infrared (IR), Nuclear Magnetic Resonance (NMR) spectra, and elemental analyses were utilized to confirm the chemical structures and purity of these compounds. In comparison to healthy noncancerous control skin fibroblast cells (BJ-1), we examined the antiproliferative efficacy of compounds (AUFU01-03) and (AUPF01-03) against specific human malignant cell lines of the breast (MCF-7), and colon (HCT-116). Based on the MTT experiment results, compounds AUFU03 and AUPF01-03 possessed highly cytotoxic effects. Among these, cytotoxicity was demonstrated by compounds AUPF01-03 with IC50 values (AUPF01, IC50 = 167 ± 0.57 µM, AUPF02, IC50 = 23.4 ± 0.68 µM and AUPF03, IC50 = 28.8 ± 1.13 µM, respectively, on MCF-7), relative to 5-Fluorouracil as reference drug (IC50 = 160.7 ± 0.22 µM). Compound AUPF01 showed safety on BJ-1 cells up to a concentration of 100 µM (% cytotoxicity = 3.9 ± 0.42 %), so AUPF01 was selected for further studies. At the gene, the expression levels of BCL-2 gene were decreased significantly in MCF-7 + 5-FU and reached the lowest level in MCF-7 + AUPF01. In contrast, the expression levels of pro-apoptotic genes (p53 and BAX) were increased in MCF-7 + 5-FU, and reached a significantly higher level in MCF-7 + AUPF01. Apoptosis/necrosis assays demonstrated that AUPF01 induced S and G2/M phase cell cycle arrest in MCF-7 cells. Moreover, the efficacy of these compounds against anti-cancer protein receptors was assessed using molecular docking. The results indicated that compound AUPF01 exhibited high binding energies, effectively interacting with the active sites of crucial proteins such as EGFR, CDK2, ERalfa, BAX1, BCL2, and P53. These interactions involved a diverse range of chemical bonding types, suggesting the potential of these substances to inhibit enzyme activities. Moreover, computational ADMET analyses of these compounds demonstrated compliance with Lipinski’s criteria, indicating favorable physicochemical properties. Additionally, molecular dynamics (MD) simulations revealed stable complexes of AUPF01 with EGFR, CDK2, ERalfa, BAX1, BCL2, and P53, as evidenced by (RMSD) values, RMSF values, and (SASA) values for the respective complexes.

The Sexual Dimorphism in Rectum and Protein Digestion Pathway Influence Sex Pheromone Synthesis in Male Bactrocera Dorsalis.

Sexual dimorphism is a crucial aspect of mating and reproduction in many animals, yet the molecular mechanisms remain unclear. In Bactrocera dorsalis, sex pheromones trimethylpyrazine (TMP) and tetramethylpyrazine (TTMP) are specifically synthesized by Bacillus strains in the male rectum. In the female rectum, Bacillus strains are found, but TMP and TTMP are not, indicating sexually dimorphic differences in sex pheromone synthesis. Our anatomical observations and precursor measurements revealed significant differences in rectal structure and ammonium levels between sexes. In vitro and in vivo experiments reveal that ammonium is vital for sex pheromone synthesis in rectal Bacillus strains. Comparative transcriptome analysis identified ammonium-producing genes (carboxypeptidase B and peptide transporter) in the protein digestion pathway that show much higher expression in the male rectum than in the female rectum. Knocking down the expression of either carboxypeptidase B (or inhibiting enzyme activity) or peptide transporter decreases rectal ammonium levels significantly, resulting in the failure of sex pheromone synthesis in the male rectum. This study provides insights into the presence of sexual dimorphism in internal organs and their functionalities in male-specific sex pheromone synthesis and has significant implications for understanding the molecular mechanisms underlying sex pheromone synthesis by symbionts in insects.

<i>In-Silico</i> Screening of Prenylated Quercetin from <i>Globimetula oreophila</i> Against <i>Plasmodium falciparum</i> Enzymes: Hope for New Antimalarial Drugs

Malaria continues to be one of the most devastating global health problems due to the high morbidity and mortality it causes in endemic regions. The search for new antimalarial targets is vital because of the increasing prevalence of drug resistance in malaria parasites. Malarial proteases constitute promising therapeutic targets as they play important roles in the parasite life cycle. The inhibition of these enzymes has pharmacological and therapeutic significance since they are involved in numerous processes, including the development, invasion, egress, and breakdown of host hemoglobin to release amino acids for parasite sustenance. In this study, <i>in silico</i> techniques were used to shed light on the mechanisms underlying the inhibitory effects of prenylated quercetin isolated from <i>Globimetula oreophila</i> on plasmepsin I and II, falciparum 2 and 3, <i>Plasmodium falciparum</i> calcium-dependent protein kinase 2, dihydrofolate reductase-thymidylate synthase, and serine repeat antigen 5. The test compound significantly interacts with key enzyme binding pockets through hydrogen bonds, van der Waals, and hydrophobic interactions, influencing protease specificity control. Crucial ligand features like carbonyl and hydroxyl groups were identified as essential for receptor interactions. Comparative analysis revealed the test compound's strong binding affinities with energies ranging from -6.4 Kcal/mol to -9.4 Kcal/mol, indicating competitive potential against various enzymes, particularly excelling against <i>Pf</i>DHFR-TS, plasmepsin-I, and SERA5 compared to native ligands. This suggests the compound's ability to competitively inhibit enzyme activity by targeting co-factor binding sites, especially with specific proteases, holding promise for therapeutic applications as potent inhibitors for the prevention and treatment of malaria.

PRODUCTION AND CHARACTERIZATION OF CELLULASES FROM ASPERGILLUS NIGER UNDER STATIC FERMENTATION

The ever-increasing uses of cellulase in various industries have made it popular among researchers. Annually, a large amount of fruit wastes go into vain, which is a great source of cellulases. The objective of this study is to use grape wastes as substrate for production of cellulases from Aspergillus niger using static fermentation. CMCase and FPase assays were performed to characterize the cellulases. The cellulases’ CMCase and FPase activities and stabilities were analyzed for optimum temperature and pH. The effect of substrate concentration and kinetic constants Km and Vmax, along with thermodynamic analysis, were determined. The effects of several metals on the activity of the enzyme were observed. The optimal temperatures were found as 40 °C and 50 °C for CMCase and FPase activity, respectively. CMCase activity shows stability at 20 °C-60 °C, FPase shows low thermal stability as its activity starts to decrease after 50 °C. CMCase and FPase both show maximum activity at pH 6, and maintain their stability at pH 6-7. The values of Km and Vmax obtained from Lineweaver and Burk plot for CMCase are 0.648 mM and 12.953 mM/min, and for FPase are 0.975 mM and 41.493 mM/min. The Arrhenius plot was used to calculate activation energy (Ea) as -19 kJ/mol, and enthalpy of reaction (ΔH) as 16.4 kJ/mol, while entropy ΔS -16.4 kJ/mol was obtained from the plot of ln(Vmax/T) versus the inverse of temperature (1/T). Most metals induce enzyme activities, whereas EDTA inhibits enzyme activities. The findings suggest A. niger has remarkable cellulase production potential from grape wastes in static fermentation, at optimum temperature and pH levels for achieving enzyme activity and stability.

A Fragment-Based Screen for Inhibitors of Escherichia coli N5-CAIR Mutase.

Although purine biosynthesis is a primary metabolic pathway, there are fundamental differences between how purines are synthesized in microbes versus humans. In humans, the purine intermediate, 4- carboxy-5-aminoimidazole ribonucleotide (CAIR) is directly synthesized from 5-aminoimidazole ribonucleotide (AIR) and carbon dioxide by the enzyme AIR carboxylase. In bacteria, yeast and fungi, CAIR is synthesized from AIR via an intermediate N5-carboxyaminoimidazole ribonucleotide (N5-CAIR) by the enzyme N5-CAIR mutase. The difference in pathways between humans and microbes indicate that N5-CAIR mutase is a potential antimicrobial drug target. To identify inhibitors of E. coli N5-CAIR mutase, a fragment-based screening campaign was conducted using a thermal shift assay and a library of 4,500 fragments. Twenty-eight fragments were initially identified that displayed dose-dependent binding to N5-CAIR mutase with Kd values ranging from 9-309 μM. Of the 28, 14 were obtained from commercial sources for retesting; however, only 5 showed dose-dependent binding to N5-CAIR mutase. The five fragments were assessed for their ability to inhibit enzyme activity. Four out of the 5 showed inhibition with Ki values of 4.8 to 159 μM. All fragments contained nitrogen heterocycles with 3 out of the 4 containing 5-membered heterocycles like those found in the substrate of the enzyme. The identified fragments show similarities to compounds identified from studies on B. anthracis N5-CAIR synthetase and human AIR carboxylase suggesting a common pharmacophore.

Impact of ultrasonic pretreatment on the color and antioxidant capacity of vacuum freeze-dried strawberries

To enhance the color quality and antioxidant potential of vacuum-freeze-dried strawberry tablets, ultrasonic waves were used as a freezing pretreatment. Results revealed that the * values of freeze − dried strawberries following ultrasonic pretreatment improved significantly by ∼60% and the C* values increased by 34.36%–51.65%. These findings suggest that ultrasonic pretreatment results in a brighter coloration of the strawberry samples. The ultrasound − assisted freezing treatment groups exhibited a significantly higher free radical scavenging ability compared with the nonultrasonic treatment group. This enhancement was attributed to the ultrasonic pretreatment, which increased the concentrations of total phenolic compounds, flavonoids, and anthocyanins, and effectively inhibited the activities of polyphenol oxidase and peroxidase, thereby reducing the content of red pigment in the strawberry samples. Furthermore, confocal laser scanning microscopy revealed a uniform distribution of sugar within the samples following ultrasonic treatment. Cluster analysis indicated that the primary indices influencing the color of the samples were total phenolic content and peroxidase activity. Therefore, the ultrasonic pretreatment method effectively enhances product color, inhibits enzyme activity, and increases anthocyanin content. This technology holds promising development prospects.

Inhibitory Effects, Fluorescence Studies, and Molecular Docking Analysis of Some Novel Pyridine-Based Compounds on Mushroom Tyrosinase.

Melanin biosynthesis in different organisms is performed by a tyrosinase action. Excessive enzyme activity and pigment accumulation result in different diseases and disorders including skin cancers, blemishes, and darkening. In fruits and vegetables, it causes unwanted browning of these products and reduces their appearance quality and economic value. Inhibiting enzyme activity and finding novel powerful and safe inhibitors are highly important in agriculture, food, medical, and pharmaceutical industries. In this regard, in the present study, some novel synthetic pyridine-based compounds including 2,6-bis (tosyloxymethyl) pyridine (compound 3), 2,6-bis (butylthiomethyl) pyridine (compound 4), and 2,6-bis (phenylthiomethyl) pyridine (compound 5) were synthesized for the first time, and their inhibitory potencies were assessed on mushroom tyrosinase diphenolase activity. The results showed that while all tested compounds significantly decreased the enzyme activity, compounds 4 and 5 had the highest inhibitory effects (respectively, 80 and 89% inhibition with the IC50 values of 17.0 and 9.0 μmol L-1), and the inhibition mechanism was mixed-type for both compounds. Ligand-binding studies were carried out by fluorescence quenching and molecular docking methods to investigate the enzyme-compound interactions. Fluorescence quenching results revealed that the compounds can form nonfluorescent complexes with the enzyme and result in quenching of its intrinsic emission by the static process. Molecular docking analyses predicted the binding positions and the amino acid residues involved in the interactions. These compounds appear to be suitable candidates for more studies on tyrosinase inhibition.

Novel cold-active amylase-producing bacterium from Chukchi Sea and its enzyme properties

A cold-active amylase was purified from Alteromonas sp. KS7913 isolated from the Chukchi Sea in the Arctic Ocean. After purification with use of ammonium sulfate precipitation, phenyl column chromatography, and size exclusion chromatography, 200.34 U mg−1 of purified amylase was obtained. The final yield was 3.4%, and the activity was 5.7-fold higher than that of the initial culture broth. KS7913 origin amylase showed a molecular weight of 70 kDa and optimal activity at 25℃, pH 7.0 in Tris-HCl buffer. The amylase was highly active, especially at 5℃, and maintained stability at basic conditions below 25℃. Copper and zinc ions inhibited enzyme activity, whereas manganese, barium, and calcium ions exhibited positive effects. This activity was maintained even in the presence of alcohol. The findings of this study supplement our understanding of cold-active amylases, and may have practical applications in low-temperature industries.

Structural characteristics of cell wall pectic polysaccharides from wampee and their decreased binding with pectinase by wampee polyphenol

To investigate the structural characteristics of cell wall pectic polysaccharides from wampee, water soluble pectin (WSP), chelator-soluble pectin (CSP) and sodium carbonate-soluble pectin (SSP) were purified. And the inhibitory effects of wampee polyphenol (WPP) on pectinase when these cell wall pectic polysaccharides were used as substrates were also explored. Purified WSP (namely PWSP) had the lowest molecular weight (8.47 × 105 Da) and the highest GalA content (33.43%). While purified CSP (called PCSP) and SSP contained more abundant rhamnogalacturonan I side chains. All of them were low-methoxy pectin (DE < 50%). Enzyme activity and kinetics analysis showed that the inhibition of pectinase by wampee polyphenol was reversible and mixed type. When SSP was used as the substrate, WPP had the strongest inhibition (IC50 = 1.96 ± 0.06 mg/mL) on pectinase. Fluorescence quenching results indicated that WPP inhibited enzyme activity by interacting with substrates and enzymes. Therefore, WPP has the application potential in controlling softening of fruits and vegetables.

Impact of Surfactants on Cumulative Trypsin Activity in Bottom-Up Proteome Analysis.

Trypsin digestion plays a pivotal role in successful bottom-up peptide characterization and quantitation. While denaturants are often incorporated to enhance protein solubility, surfactants are recognized to inhibit enzyme activity. However, several reports have suggested that incorporating surfactants or other solvent additives may enhance digestion and MS detection. Here, we assess the impacts of ionic surfactants on cumulative trypsin activity and subsequently evaluate the total digestion efficiency of a proteome mixture by quantitative MS. Although low surfactant concentrations, such as 0.01% SDS or 0.2% SDC, significantly enhanced the initial trypsin activity (by 14 or 42%, respectively), time course assays revealed accelerated enzyme deactivation, evident by 10- or 40-fold reductions in trypsin activity half-life at these respective surfactant concentrations. Despite enhanced initial tryptic activity, quantitative MS analysis of a common liver proteome extract, digested with various surfactants (0.01 or 0.1% SDS, 0.5% SDC), consistently revealed decreased peptide counts and signal intensity, indicative of a lower digestion efficiency compared to a nonsurfactant control. Furthermore, including detergents for digestion did not improve the detection of membrane proteins, nor hydrophobic peptides. These results stress the importance of assessing cumulative enzyme activity when optimizing the digestion of a proteome mixture, particularly in the presence of denaturants.

Comprehending the inhibition mechanism of indole-based bis-acylhydrazone compounds on α-glucosidase: Spectral and theoretical approaches

Indole-based bis-acylhydrazone compounds can inhibit the activity of α-glucosidase and control the concentration of blood glucose. In this paper, the characteristics of three indole-based bis-acylhydrazone compounds with different inhibitory activities of α-glucosidase as well as the interaction with α-glucosidase were studied by experiments and computational simulation techniques. Enzyme kinetic and spectral experiments showed that the indole-based bis-acylhydrazone compounds were able to inhibit enzyme activity through mixed inhibition dominated by competitive inhibition, and during the binding reaction, indole-based bis-acylhydrazone compounds can quench the intrinsic fluorescence of α-glucosidase through static quenching and an aggregation of the indole-based bis-acylhydrazone with α-glucosidase produces a stable complex with a molar ratio of 1:1, and the combination of indole-based bis-acylhydrazone compounds could lead to slight change in the conformation of α-glucosidase. The theoretical simulation demonstrated that the stability of the complex systems was positively correlated with the inhibitory activity of indole-based bis-acylhydrazone compounds, and the indole-based bis-acylhydrazone compounds occupied the active site in the multi-ligand system, resulting in a significant decrease in the binding ability of starch to active amino acids. These results suggested that indole-based bis-acylhydrazone compound was expected to be a new type of α-glucosidase inhibitor.

Comprehensive approach to in silico identification and in vitro validation of anti-filarial hit molecules targeting the dimer interface of thioredoxin peroxidase 1 in Wuchereria bancrofti: a progress in anti-filariasis drug development.

Lymphatic filariasis (LF) remains a significant health challenge for populations in developing countries. LF is a parasitic disease transmitted by mosquitoes, mainly caused by the filarial nematode, Wuchereria bancrofti, prevalent in tropical and subtropical regions. Since the present drugs develop complications, including adverse side effects, lack of specificity, and development of drug resistance, the present study focused on developing the potential anti-filariasis drugs targeting crucial proteins for the nematode life cycle. We have identified the therapeutic compounds by targeting the enzyme thioredoxin peroxidase 1 (WbTPx1), which facilitates the conversion of hydrogen peroxide into water, an essential mechanism by which the nematode survives against oxidative stress in the host. This approach might resolve treatment efficacy and activity difficulties at various stages of filarial parasitic worms. We modeled the structure of WbTPx1 and employed the structure-based virtual screening approach, focusing on the dimer interface region of the protein. ADMET prediction profiles of the non-toxic, top-ranked hits with higher docking scores demonstrate higher affinity to the nematode protein than its human homolog. The molecular dynamic simulation studies show WbTPx1-hit complexes' stability and the intactness of hits in the binding site. Further, in vitro validation of identified hits using Setaria digitata, a cattle nematode, showed better IC50 and higher inhibition than the standard drug ivermectin, indicating the potential to inhibit enzyme activity and the development of drug candidates for controlling LF.

Effect of Near-Freezing Temperature Storage on the Quality and Organic Acid Metabolism of Apple Fruit

Organic acids play critical roles in fruit physiological metabolism and sensory quality. However, the conventional storage of apple fruit at 0 ± 0.1 °C cannot maintain fruit acidity efficiently. This study investigated near-freezing temperature (NFT) storage for ‘Golden Delicious’ apples, and the quality parameters, organic acid content, and malate metabolism were studied. The results indicate that NFT storage at −1.7 ± 0.1 °C effectively maintained the postharvest quality of apple fruit when compared to traditional storage at 0 ± 0.1 °C. Fruit that underwent NFT storage showed a better appearance and lower respiratory rate, ethylene production, weight loss, and malondialdehyde (MDA) content but higher firmness and soluble solids content. Further, fruit after NFT storage contained higher titratable acid (18.75%), malate (51.61%), citrate (36.59%), and succinate (2.12%) content when compared to the control after 250 days. This was achieved by maintaining higher cytosolic NAD-dependent malate dehydrogenase (cyNAD-MDH), phosphoenolpyruvate carboxylase (PEPC), vacuolar H+-ATPase (V-ATPase), and vacuolar inorganic pyrophosphatase (V-PPase) activities that promote malate biosynthesis and accumulation while inhibiting enzyme activity that is responsible for malate decomposition, including phosphoenolpyruvate carboxylase kinase (PEPCK) as well as the cytosolic NAD phosphate-dependent malic enzyme (cyNADP-ME). Further, storage at NFTs maintained a higher expression of malate biosynthesis-related genes (MdcyNAD-MDH and MdPEPC) and transport-related genes (MdVHA and MdVHP) while suppressing malate consumption-related genes (MdcyME and MdPEPCK). The results demonstrate that NFT storage could be an effective application for apple fruit, which maintains postharvest quality and alleviates organic acid degradation.

Green modifications for rendering cotton fabric with antibacterial, anti-mite, and mosquito-repellent functions using single natural eugenol

Cotton fabrics are widely used in everyday life; however, increasing their versatility through green modifications remains a challenge. The current mainstream approach merely physically attaches the additives onto the fibers, resulting in low binding affinity. In this study, novel cotton fabrics (Cotton-Si-EU) with long-lasting antibacterial, anti-mite, and mosquito-repellent properties were facilely fabricated in a green procedure. In contrast to conventional coating and physical addition methods, the eugenol graft modification ensured the safety, environmental friendliness and long-lasting functionality of the Cotton-Si-EU. In addition, Cotton-Si-EU fabrics retained the softness, comfort, breathability, and moisture absorption originating from the cotton fabric. Cotton-Si-EU also showed over 99.99% antibacterial, 73% anti-mite, and 75% mosquito repellent rates, simultaneously destroying microorganisms and insects through oxidative stress, inhibiting enzyme activity, affecting cell structure, and other mechanisms. More importantly, after 50 washing cycles, the fabrics still exhibited durable antibacterial properties higher than the AAA requirements, indicating high functional longevity. In addition, good cytocompatibility, hemocompatibility, and negligible skin irritation demonstrated excellent biological safety. Therefore, this study is of great significance in providing a reference for modifying cotton fabrics using an infinite number of natural products after screening, which will broaden the application scope and improve the safety level of functional cotton fabrics.

The Metabolism, Detrimental Effects, and Signal Transduction Mechanism of Reactive Oxygen Species in Plants under Abiotic Stress

Plants are a major source of bio based materials, and their productivity is significantly impacted by environmental adversities with the continuous deterioration of the environment. The disruption of reactive oxygen species (ROS) production and scavenging balance is a common consequence of various abiotic stresses in plants, resulting in the excessive accumulation of ROS. However, it is crucial to acknowledging the dual role of ROS, acting both as harmful substances and signaling molecules. ROS can interact with membrane proteins, initiating a chain reaction of membrane lipid peroxidation. This process leads to a decrease in membrane lipid unsaturation and fluidity, as well as an increase in membrane permeability. Inhibited enzyme activity even lead to loss of protein function, caused DNA damage and mutations, blocked DNA replication and transcription, eventually leading to cell death. This can result in significant reductions in crop yield and biomass in bio based agricultural production. ROS also played vital role in signal molecule transduction in the process of plant resistance to stress, and worked in concert with other signal molecules to induce the stress resistance genes’ expression and enhance plant resistance. Hereto, scavenging mechanism for ROS in plants is of the essence to regulate the concentration of ROS, thus determining which role ROS play. The thermal dissipation of excess light energy effectively avoids ROS production, and the enzymatic and non-enzymatic antioxidant defense systems in plants work cooperatively to clear excessive ROS. This review provides a comprehensive summary of the production pathway, detrimental effects, scavenging mechanism and signal transduction of ROS in plants under abiotic stress.

Application of Enzyme Inhibition Therapy in the Management/Treatment of Neurological Conditions, Diseases, and Disorders

Enzyme inhibition therapy uses specific molecules to inhibit enzyme activity, targeting disease-related enzymes in medical treatments like cancer treatment and infectious disease management. Different types of inhibitors, competitive and non-competitive, bind to different sites and alter enzyme function. The success of this therapy depends on the inhibitor's specificity and delivery to the target site. Further research could lead to more effective treatments. Nowadays, the majority of medications are enzyme inhibitors and are in the clinical or pre-clinical stages of drug development. Enzyme inhibitors are often prescribed medications for a variety of illnesses, including neurological problems. There is only symptomatic therapy available for many neurological conditions, particularly neuro-degenerative disorders, as opposed to therapy based on knowledge of the underlying mechanisms of these diseases. Enzyme inhibitors are useful as they block the function of certain enzymes whose aberrant activity could be contributing to the illness. They also alleviate the symptoms and stop the disease’s progression. This review discusses the mechanism of action of several enzyme inhibitors that have been prescribed as medications for neurological illnesses as well as some that are still in research stages.

The interaction mechanism of tepotinib and α-glucosidase: A prelude to control type 2 diabetes mellitus

α-Glucosidase is associated with the enhancement in postprandial blood glucose. Therefore, inhibition of α-glucosidase activity could be considered as a potential strategy to control type 2 diabetes mellitus (DM). Tepotinib (TPT) as an enzyme inhibitor with a molecular formula of C29H28N6O2 has a distinct structure that may make it useful for interacting with α-glucosidase, causing conformational changes and inhibiting enzyme activity. In this study, the interaction mechanism of TPT and α-glucosidase was explored. The enzyme activity assay showed that TPT could inhibit α-glucosidase activity with the IC50 value of 0.071 ± 0.007 mg/mL (164 ± 16.5 µM), which was comparable with that of acarbose (IC50 = 0.045 ± 0.006 mg/mL = 255 ± 38.25 µM) as a clinical drug. It was further determined that Ser 241 and His 280 amino acid residues in the active site assist in the formation of the TPT-α-glucosidase complex mediated by hydrogen bonding and van der Waals forces, which might lead to the conformational folding of α-glucosidase to some extent. Additionally, the interaction of TPT and α-glucosidase reduced the surface hydrophobicity of the enzyme and altered the microenvironment around Tyr 158 amino acid residue in the active site. These findings suggested that TPT might be employed as a potential inhibitor of α-glucosidase activity, suggesting that it should be further explored in future studies to develop a TPT-based system for application in the amelioration of DM.

Evaluating the effects of metal ions on malate dehydrogenase enzyme activity in Watermelon.

Malate Dehydrogenase (MDH) is an essential enzyme in the cellular respiration pathway known as the Tricarboxylic Acid Cycle. Using NAD+ or NADP+ as a cofactor, MDH catalyzes the reversible conversion of oxaloacetate to malate. It can be found in plants, bacteria, and animals. However, some metal ions, such as Cu2+, Zn2+, and Pb2+, can decrease MDH activity. In this study, the recombinant MDH protein (His-MDH) of watermelon was purified and quality tested by SDS-PAGE. The average protein concentrations of elution, cell lysate, and wash were 0.37 mg/mL, 2.23 mg/mL, and 0.24 mg/mL, respectively. According to SDS-PAGE, the size of the purified protein was approximately 37 kD, suggesting the purification of the correct protein. The enzyme activity of the MDH protein will be tested in the presence of metal ions such as MgSO4, NiSO4, ZnSO4, CuSO4, and PdCl2, which have been shown to inhibit dehydrogenase enzymes. Our results provide valuable insight on how different metal ions present in the environment can affect the cell respiration of organisms by affecting the malate dehydrogenase enzyme. Further studies on the roles of metal ions in the TCA cycle and related metabolism, as well as the mechanisms by which metal ions inhibit enzyme activity, will be beneficial in understanding ways to improve soil conditions for higher crop production and for the understanding of evolutionary processes.

A combined approach of lauroyl arginine ethyl ester hydrochloride and kojic acid in mitigating fresh-cut potato deterioration

The combinational effects of kojic acid and lauroyl arginine ethyl ester hydrochloride (ELAH) on fresh-cut potatoes were investigated. Kojic acid of 0.6% (w/w) effectively inhibited the browning of fresh-cut potatoes and displayed antimicrobial capacity. The color difference value of samples was decreased from 175 to 26 by kojic acid. In contrast, ELAH could not effectively bind with the active sites of tyrosinase and catechol oxidase at molecular level. Although 0.5% (w/w) of ELAH prominently inhibited the microbial growth, it promoted the browning of samples. However, combining kojic acid and ELAH effectively inhibited the browning of samples and microbial growth during the storage and the color difference value of samples was decreased to 52. This amount of kojic acid inhibited enzyme activities toward phenolic compounds. The results indicated that combination of kojic acid and ELAH could provide a potential strategy to extend the shelf life of fresh-cut products.

Inositol-Exchange Activity in Human Primordial Placenta.

Human placenta is an intensively growing tissue. Phosphatidylinositol (PI) and its derivatives are part of the signaling pathway in the regulation of trophoblast cell differentiation. There are two different enzymes that take part in the direct PI synthesis: phosphatidylinositol synthase (PIS) and inositol exchange enzyme (IE). The presence of PIS is known in the human placenta, but IE activity has not been documented before. In our study, we describe the physiological properties of the two enzymes in vitro. PIS and IE were studied in different Mn2+ and Mg2+ concentrations that enabled us to separate the individual enzyme activities. Enzyme activity was measured by incorporation of 3[H]inositol in human primordial placenta tissue or microsomes. Optimal PIS activity was achieved between 0.5 and 2.0 mM Mn2+ concentration, but higher concentrations inhibit enzyme activity. In the presence of Mg2+, the enzyme activity increases continuously up to a concentration of 100 mM. PIS was inhibited by nucleoside di- and tri-phosphates. PI production increases between 0.1 and 10 mM Mn2+ concentration. The incorporation of [3H]inositol into PI increased by 57% when adding stabile GTP analog. The described novel pathway of inositol synthesis may provide an additional therapeutic approach of inositol supplementation before and during pregnancy.