Molecular Mechanism Of Action Research Articles

Effective action of silymarin against ketamine-induced schizophrenia in male mice: Insight into the biochemical and molecular mechanisms of action

BackgroundNeurochemical dysregulations resulting from N-methyl-D-aspartate hypofunction (NMDA), are exacerbated by neuroimmune and oxidative stress and are known risk factors for neuropsychiatric disorders like schizophrenia-like diseases. Here, we investigate the protective and curative effects, and mechanisms of silymarin, a polyphenolic flavonoid with neuroprotective functions in preventive-reversal model of ketamine, an NMDA antagonist in mice. MethodsMice were grouped into 6 cohorts (n = 9). In the pre-treatment, groups 1 and 2 received saline (10 mL/kg/p.o.), groups 3 and 4 (silymarin, 50 and 100 mg/kg/p.o.), and group 5 (risperidone, 0.5 mg/kg/p.o.) consecutively for 14 days, then combined with ketamine (20 mg/kg/i.p.) injection in groups 2–5 from days 8–14. However, mice in reversal study received intraperitoneal injection of ketamine for 14 days before silymarin (50 and 100 mg/kg, p.o) and risperidone (0.5 mg/kg, p.o.) treatment between days 8–14. The consequences on schizophrenia-like behavior, neurochemistry, inflammation, and oxidative/nitrergic stress markers were evaluated in critical brain regions of the disease. ResultsSilymarin prevented and reversed ketamine-induced increase in dopamine, 5-hydroxyltryptamine, acetylcholinesterase, malondialdehyde and nitrite levels in the striatum, prefrontal-cortex and hippocampus. These were accompanied by improvement in hyperlocomotion, stereotypy, memory, and social impairments, notably devoid of cataleptogenic potential. Complementarily, silymarin reduced myeloperoxidase, tumor-necrosis factor-α, and interleukin-6 concentrations relative to the ketamine group. Moreover, ketamine-induced decreased brain-derived neurotrophic factor, glutathione, catalase, superoxide-dismutase levels were normalized by silymarin in the brain regions relative to ketamine. ConclusionsOverall, these findings suggest that silymarin's antipsychotic effect might be primarily associated, among other mechanisms, with the normalization of neurochemical and neurotrophic changes in the mice brains.

Free Energy Analysis of Peptide-Induced Pore Formation in Lipid Membranes by Bridging Atomistic and Coarse-Grained Simulations.

Antimicrobial peptides (AMPs) are attractive materials for combating the antimicrobial resistance crisis because they can kill target microbes by directly disrupting cell membranes. Although thousands of AMPs have been discovered, their molecular mechanisms of action are still poorly understood. One broad mechanism for membrane disruption is the formation of membrane-spanning hydrophilic pores which can be stabilized by AMPs. In this study, we use molecular dynamics simulations to investigate the thermodynamics of pore formation in model single-component lipid membranes in the presence of one of three AMPs: aurein 1.2, melittin and magainin 2. To overcome the general challenge of modeling long time scale membrane-related behaviors, including AMP binding, clustering, and pore formation, we develop a generalizable methodology for sampling AMP-induced pore formation. This approach involves the long equilibration of peptides around a pore created with a nucleation collective variable by performing coarse-grained simulations, then backmapping equilibrated AMP-membrane configurations to all-atom resolution. We then perform all-atom simulations to resolve free energy profiles for pore formation while accurately modeling the interplay of lipid-peptide-solvent interactions that dictate pore formation free energies. Using this approach, we quantify free energy barriers for pore formation without direct biases on peptides or whole lipids, allowing us to investigate mechanisms of pore formation for these 3 AMPs that are a consequence of unbiased peptide diffusion and clustering. Further analysis of simulation trajectories then relates variations in pore lining by AMPs, AMP-induced lipid disruptions, and salt bridges between AMPs to the observed pore formation free energies and corresponding mechanisms. This methodology and mechanistic analysis have the potential to generalize beyond the AMPs in this study to improve our understanding of pore formation by AMPs and related antimicrobial materials.

Small Molecule NS11021 Promotes BK Channel Activation by Increasing Inner Pore Hydration.

The Ca2+ and voltage-gated big potassium (BK) channels are implicated in various diseases, including heart disease, asthma, epilepsy, and cancer, but remain an elusive drug target. A class of negatively charged activators (NCAs) have been demonstrated to promote the activation of several potassium channels including BK channels by binding to the hydrophobic inner pore, yet the underlying molecular mechanism of action remains poorly understood. In this work, we analyze the binding mode and potential activation mechanism of a specific NCA named NS11021 using atomistic simulations. The results show that NS11021 binding to the pore in deactivated BK channels is nonspecific and dynamic. The binding free energy of -8.3 ± 0.7 kcal/mol (KD = 0.3-3.1 μM) calculated using umbrella sampling agrees quantitatively with the experimental EC50 range of 0.4-2.1 μM. The bound NS11021 remains dynamic and is distal from the filter to significantly impact its conformation. Instead, NS11021 binding significantly enhances the pore hydration due to the charged tetrazol-phenyl group, thereby promoting the opening of the hydrophobic gate. We further show that the free energy barrier to K+ permeation is reduced by ∼3 kcal/mol regardless of the binding pose, which could explain the ∼62-fold increase in the intrinsic opening of BK channels measured experimentally. Taken together, these results support the idea that the molecular mechanism of NS11021 derives from increasing the hydration level of the conformationally closed pore, which does not depend on specific binding and likely explains the ability of NCAs to activate multiple K+ channels.

Novel therapeutic approach for psoriasis: Upregulating FcRn to inhibit ferroptosis and alleviate lesional skin

Psoriasis, a chronic inflammatory skin disease, is characterized by complex immune dysregulation and oxidative stress responses. The neonatal Fc receptor (FcRn) plays a crucial role in the development of autoimmune diseases. Analysis of clinical psoriasis samples demonstrated a negative correlation between FcRn expression in skin lesions and disease severity. However, the role of FcRn in this process remains unclear. This study aimed to investigate the involvement of FcRn in the pathogenesis and progression of psoriasis. In an imiquimod (IMQ)-induced psoriasis-like mouse model, FcRn expression was significantly decreased in the lesional skin, and transcriptome sequencing of the skin revealed activation of the ferroptosis pathway in psoriasis. This led to the hypothesis that FcRn could potentially regulate ferroptosis via the signal transducer and activating transcription factor 3 (STAT3)/solute carrier family 7 member 11 (SLC7A11) axis. Further experiments showed exacerbated psoriasis-like lesional skin and ferroptosis in FcRn-knockout mice, whereas intervention with the ferroptosis inhibitor Fer-1 or STAT3 inhibitor Stattic alleviated these symptoms. Critical binding sites for the transcription factor STAT3 were identified in the SLC7A11 promoter region at positions −1185 and −564 using the luciferase reporter assays and chromatin immunoprecipitation. The administration of 1,4-naphthoquinone (NQ), an FcRn agonist, effectively alleviated psoriasis-like skin lesions by inhibiting ferroptosis. This study highlights the molecular mechanisms of action of FcRn in psoriasis and provides an experimental basis for the development of novel therapeutic strategies targeting FcRn.

Pathophysiology of Arginases in Cancer and Efforts in Their Pharmacological Inhibition.

Arginases are key enzymes that hydrolyze L-arginine to urea and L-ornithine in the urea cycle. The two arginase isoforms, arginase 1 (ARG1) and arginase 2 (ARG2), regulate the proliferation of cancer cells, migration, and apoptosis; affect immunosuppression; and promote the synthesis of polyamines, leading to the development of cancer. Arginases also compete with nitric oxide synthase (NOS) for L-arginine, and their participation has also been confirmed in cardiovascular diseases, stroke, and inflammation. Due to the fact that arginases play a crucial role in the development of various types of diseases, finding an appropriate candidate to inhibit the activity of these enzymes would be beneficial for the therapy of many human diseases. In this review, based on numerous experimental, preclinical, and clinical studies, we provide a comprehensive overview of the biological and physiological functions of ARG1 and ARG2, their molecular mechanisms of action, and affected metabolic pathways. We summarize the recent clinical trials' advances in targeting arginases and describe potential future drugs.

Lunasin: A Medicinally Important Chemo-Preventive Natural Dietary Pe

Lunasin is a natural peptide of plant origin possessing potential activity against chronic disorders specially cancer along with associated cardiovascular diseases. The bioavailability and confirmed effectiveness against breast, skin and colorectal cancer has declared lunasin as a promising chemo-preventive agent. Lunasin, a 43 amino acids long peptide possess anti-inflammatory and anti-oxidative activity. Modern biotechnological techniques viz. genomics, proteomics along with other biochemical tools are continuously elucidating the molecular mechanisms of lunacin action. Lunasin enriched natural product-based healthcare remedies for the prevention of life style induced cancer is suggested as an alternative to the conventional chemo, immuno and hormonal therapy.

Exploring the hepatoprotective properties of citronellol: In vitro and in silico studies on ethanol-induced damage in HepG2 cells.

Citronellol (CT) is a monoterpene alcohol present in the essential oil of plants of the genus Cymbopogon and exhibits diverse pharmacological activities. The aim of the current study was to investigate the hepatoprotective potential of CT against ethanol-induced toxicity in HepG2 cell lines. Silymarin (SIL) was used as a standard drug. MTT, crystal violet assay, DAPI, and PI staining were carried out to assess the effect of ethanol and CT on cell viability. RT-PCR determined the molecular mechanisms of hepatoprotective action of CT. CT ameliorated cell viability and restricted ethanol-induced cell death. DAPI and PI staining showed distinct differences in cell number and morphology. Less cell viability was observed in the diseased group obviously from strong PI staining when compared to the CT- and SIL-treated group. Moreover, CT showed downregulation of interleukin (IL-6), transforming growth factor-beta 1 (TGF-β1), collagen type 1 A 1 (COL1A1), matrix metalloproteinase-1 (MMP-1), tissue inhibitor of metalloproteinase-1 (TIMP-1) and glutathione peroxidase-7 (GPX-7) levels. Molecular docking studies supported the biochemical findings. It is concluded that the cytoprotective activity of CT against ethanol-induced toxicity might be explained by its anti-inflammatory, immunomodulatory, and collagen-regulating effects.

Exploring TβRI inhibitors from Arenaria kansuensis based on 3D-QSAR, molecular docking and molecular dynamics simulation methods and its anti-pulmonary fibrosis molecular mechanism validation

Ethnopharmacological relevancePulmonary fibrosis (PF) is a kind of interstitial lung disease that seriously threatens human life and health. Up to now, there is no specifically therapeutic drug. Arenaria kansuensis, a typical Tibetan medicine, has been previously proved to have anti-PF pharmacological activity by our group. However, the specific target and molecular mechanism of pharmacological active ingredients from it are still unknown. Aim of the studyThis study aimed to explore the molecular mechanism and specific target of pharmacological active ingredients from A. kansuensis for treating PF. Materials and methodsVirtual screening including 3D-QSAR, molecular docking and molecular dynamics simulation were used to screen TβRI inhibitor. CETSA experiment was used to verify the interaction between GAK (a β-carboline alkaloid isolated from A. kansuensis) and TβRI. Cell and molecular experiments including observation of cell morphology and Western blot were applied to investigate the molecular mechanism of action of GAK for treating PF. Animal experiments including physiological index, immunohistochemistry and ELISA were used to comprehensively evaluate the anti-PF effect of GAK and explore the corresponding mechanism of action. ResultsResults of 3D-QSAR experiment indicated that GAK is a much stronger potential TβRI inhibitor, molecular mechanism study showed that 30 μM GAK could significantly keep TβRI more stable which indicated that the direct binding interaction between GAK and TβRI, it targetedly inhibited TβRI through forming hydrogen bonds with LYS232, SER280 and ASP351 and the binding energies is −56.05 kcal/mol.In vitro experiment showed GAK could suppress downstream signal pathways of TβRI including MAPK, PI3K/AKT and NF-κB pathways during EMT process. In vivo experiment showed that GAK could improve the survival rate and body weight of PF mice, alleviate the symptoms of histopathological severity, inflammatory cell infiltration and collagen deposition in lung tissue of PF mice through inhibiting EMT process of PF. ConclusionsThis work not only provided evidence to support GAK as a novel TβRI inhibitor for treating PF through multiple pathways, but also reveal the specific target and molecular mechanism of β-carboline alkaloids from A. kansuensis for treating PF.

Turmeric Essential Oil Constituents as Potential Drug Candidates: A Comprehensive Overview of Their Individual Bioactivities.

The therapeutic properties of turmeric essential oil have been extensively documented in both preclinical and clinical studies. Research indicates that its primary active compounds are promising candidates for addressing a wide range of pathologies, exhibiting anticancer, anti-inflammation, antioxidant, cardiovascular, hypoglycemic, dermatological, hepatoprotective, neurological, antiparasitic, antiviral, insecticidal, antifungal, and antivenom activities. While numerous compounds possess similar potential applications, the isolated active constituents of turmeric essential oil stand out due to their unique pharmacological profiles and absence of toxicity. This literature review meticulously compiles and analyzes the bioactivities of these constituents, emphasizing their molecular mechanisms of action, reported pharmacological effects, and potential therapeutic applications. The aim of this review is to provide a comprehensive synthesis of currently available clinical and preclinical findings related to individual turmeric essential oil compounds, while also identifying critical knowledge gaps. By summarizing these findings, this work encourages further research into the isolated compounds from turmeric oil as viable drug candidates, ultimately contributing to the development of innovative therapeutic strategies.

Exploring the molecular mechanism of anti-inflammatory action of Coriandrum sativum using network pharmacology, molecular dynamic simulation, and density functional theory

Exploring the molecular mechanism of anti-inflammatory action of Coriandrum sativum using network pharmacology, molecular dynamic simulation, and density functional theory

Phosphorylation activates master growth regulator DELLA by promoting histone H2A binding at chromatin in Arabidopsis

DELLA proteins are conserved master growth regulators that play a central role in controlling plant development in response to internal and environmental cues. DELLAs function as transcription regulators, which are recruited to target promoters by binding to transcription factors (TFs) and histone H2A via their GRAS domain. Recent studies showed that DELLA stability is regulated post-translationally via two mechanisms, phytohormone gibberellin-induced polyubiquitination for its rapid degradation, and Small Ubiquitin-like Modifier (SUMO)-conjugation to increase its accumulation. Moreover, DELLA activity is dynamically modulated by two distinct glycosylations: DELLA-TF interactions are enhanced by O-fucosylation, but inhibited by O-linked N-acetylglucosamine (O-GlcNAc) modification. However, the role of DELLA phosphorylation remains unclear as previous studies showing conflicting results ranging from findings that suggest phosphorylation promotes or reduces DELLA degradation to others indicating it has no effect on its stability. Here, we identify phosphorylation sites in REPRESSOR OF ga1-3 (RGA, an AtDELLA) purified from Arabidopsis by mass spectrometry analysis, and show that phosphorylation of two RGA peptides in the PolyS and PolyS/T regions enhances RGA activity by promoting H2A binding and RGA association with target promoters. Notably, phosphorylation does not affect RGA-TF interactions or RGA stability. Our study has uncovered a molecular mechanism of phosphorylation-induced DELLA activity.

Paeoniflorin inhibits PRAS40 interaction with Raptor to activate mTORC1 to reverse excessive autophagy in airway epithelial cells for asthma

BackgroundBronchial asthma is a chronic condition characterized by airway inflammation and remodeling, which pose complex pathophysiological challenges. Autophagy has been identified as a practical strategy to regulate inflammation and remodeling processes in chronic inflammatory diseases with pathological characteristics, such as asthma. PF (Paeoniflorin) is a potential new autophagy regulatory compound. Previous studies have reported that PF can inhibit airway inflammation to alleviate allergic asthma, but whether this is mediated through the regulation of autophagy and the molecular mechanism of action remains unclear. PurposeThe aim of this study was to evaluate the inhibitory effect of natural small molecule PF on asthma by regulating epithelial autophagy. MethodsThe rat asthma model was established through intraperitoneal injection of OVA and aluminum hydroxide suspension, followed by atomized inhalation of OVA for a period of two weeks. Following treatment with PF, histopathology was observed using Masson and H&E staining, while airway Max Rrs was evaluated using a pulmonary function apparatus. Levels of inflammatory cells in BALF were detected using a blood cell analyzer, and levels of inflammatory factors in BALF were detected through Elisa. Expressions of p-PRAS40 and p-Raptor were observed through immunohistochemistry, and levels of Beclin1 and LC3B were observed through immunofluorescence. The structure and quantity of autophagosomes and autophagolysosomal were observed through TEM. An autophagy model of 16HBE cells was established after treatment with 10ng/mL IL13 for 30 minutes. PRAS40 (AKT1S1) overexpression and mutation of PF and Raptor binding site (K207M& L302I& Q417H) were introduced in 16HBE cells. Autophagy in cells was measured by mFRP-GFP-LC3 ADV fluorescent tracer. The binding sites of PF and Raptor were analyzed using the Autodock Tool. The p-mTOR, p-Raptor, p-PRAS40, LC3II/LC3I were detected through Western blot, and interaction between PRAS40-Raptor and Raptor-mTOR was detected through Co-IP. ResultsThe results showed that PF effectively reduced airway inflammation, improved airway pathological changes and remodeling, and maintained lung function. Additionally, PF was found to reverse excessive autophagy in airway epithelial cells. Interestingly, PF activated the mTORC1 subunit PRAS40 and Raptor in airway epithelial cells by regulating their phosphorylation. PRAS40 is an endogenous mTOR inhibitor that promotes autophagy. PF competitively binds Raptor to PRAS40, promoting Raptor-mTOR interactions to activate mTORC1, an outcome that can be reversed by PRAS40 overexpression and site-specific amino acid codon mutations in Raptor. ConclusionThese findings suggest that PF intervention and inhibition of PRAS40-Raptor interaction are effective treatments for bronchial asthma. By activating mTORC1, PF effectively reverses excessive autophagy in airway epithelial cells, leading to improved airway function and reduced inflammation.

Proteomic analysis reveals the dominant effect of ipomoeassin F on the synthesis of membrane and secretory proteins in triple-negative breast cancer cells.

Ipomoeassin F (Ipom-F) is a natural compound with embedded carbohydrates that exhibits a potent cytotoxic effect on triple-negative breast cancer (TNBC) cells. The mechanism behind this selective potency remains unclear. To elucidate this mechanism, we analyzed the proteome profiles of the TNBC MDA-MB-231 cells after exposure to Ipom-F at different time points and increasing doses using a quantitative proteomic method. Our proteomic data demonstrate that the major effect of Ipom-F on MDA-MB-231 cells is the inhibition of membrane and secreted protein expression. Our proteomic data are consistent with the recently uncovered molecular mechanism of action of Ipom-F, which binds to Sec61-α and inhibits the co-translational import of proteins into the endoplasmic reticulum. We have defined a subset of membrane and secreted proteins particularly sensitive to Ipom-F. Analysis of the expression of these Ipom-F-sensitive proteins in cancer cell lines and breast cancer tissues demonstrates that some of these proteins are upregulated in TNBC cells. Thus, it is likely that TNBC cells may have adapted to the elevated levels of some proteins identified as sensitive to Ipom-F in this study; inhibition of the expression of these proteins leads to a crisis in proliferation and/or survival for the cells.

Microtubule-associated protein, MAP1B, encodes functionally distinct polypeptides

Microtubule-associated protein, MAP1B, is crucial for neuronal morphogenesis and disruptions in MAP1B function are correlated with neurodevelopmental disorders. MAP1B encodes a single polypeptide that is processed into discrete proteins, a heavy chain (HC) and a light chain (LC); however, it is unclear if these two chains operate individually or as a complex within the cell. In vivo studies have characterized the contribution of MAP1B HC and LC to microtubule and actin-based processes, but their molecular mechanisms of action are unknown. Using in vitro reconstitution with purified proteins, we dissect the biophysical properties of the HC and LC and uncover distinct binding behaviors and functional roles for these MAPs. Our biochemical assays indicate that MAP1B HC and LC do not form a constitutive complex, supporting the hypothesis that these proteins operate independently within cells. Both HC and LC inhibit the microtubule motors, kinesin-3, kinesin-4, and dynein, and differentially affect the severing activity of spastin. Notably, MAP1B LC binds to actin filaments in vitro and can simultaneously bind and crosslink actin filaments and microtubules, a function not observed for MAP1B HC. Phosphorylation of MAP1B HC by DYRK1a negatively regulates its actin-binding activity without significantly affecting its microtubule-binding capacity, suggesting a dynamic contribution of MAP1B HC in cytoskeletal organization. Overall, our study provides new insights into the distinct functional properties of MAP1B HC and LC, underscoring their roles in coordinating cytoskeletal networks during neuronal development.

Human toxin-like SLURP-1 protein as a prototype of anticancer drugs: Molecular mechanisms of action in vivo

Human toxin-like SLURP-1 protein as a prototype of anticancer drugs: Molecular mechanisms of action in vivo

WTAP participates in neuronal damage by protein translation of NLRP3 in an m6A-YTHDF1-dependent manner after traumatic brain injury.

Traumatic brain injury (TBI) is a common complication of acute and severe neurosurgery. Remodeling of N6-methyladenosine (m6A) stabilization may be an attractive treatment option for neurological dysfunction after TBI. In the present study, the authors explored the epigenetic methylation of RNA-mediated NLRP3 inflammasome activation after TBI. Neurological dysfunction, histopathology, and associated molecules were examined in conditional knockout (CKO) WTAP [flox/flox, Camk2a-cre] , WTAP flox/flox , and pAAV-U6-shRNA-YTHDF1-transfected mice. Primary neurons were used in vitro to further explore the molecular mechanisms of action of WTAP/YTHDF1 following neural damage. The authors found that WTAP and m6A levels were upregulated at an early stage after TBI, and conditional deletion of WTAP in neurons did not affect neurological function but promoted functional recovery after TBI. Conditional deletion of WTAP in neurons suppressed neuroinflammation at the TBI early phase: WTAP could directly act on NLRP3 mRNA, regulate NLRP3 mRNA m6A level, and promote NLRP3 expression after neuronal injury. Further investigation found that YTH domain of YTHDF1 could directly bind to NLRP3 mRNA and regulate NLRP3 protein expression. YTHDF1 mutation or silencing improved neuronal injury, inhibited Caspase-1 activation, and decreased IL-1β levels. This effect was mediated via suppression of NLRP3 protein translation, which also reversed the stimulative effect of WTAP overexpression on NLRP3 expression and inflammation. Our results indicate that WTAP participates in neuronal damage by protein translation of NLRP3 in an m6A-YTHDF1-dependent manner after TBI and that WTAP/m6A/YTHDF1 downregulation therapeutics is a viable and promising approach for preserving neuronal function after TBI, which can provide support for targeted drug development.

The molecular mechanism of action of snake venom toxins – a computational perspective

The molecular mechanism of action of snake venom toxins – a computational perspective

Molecular Mechanism and Actions of Antifungal Drugs Using Trichosporon Fungal Species

Molecular Mechanism and Actions of Antifungal Drugs Using Trichosporon Fungal Species

Ballota hirsuta essential oil as a potential multitarget agent against Leishmania parasite: in vitro and in silico studies.

In the present study, we assessed the antioxidant and antileishmanial potential from fresh leaves of Ballota (B.) hirsuta essential oil (EO). The GC-MS analysis of B. hirsuta EO revealed that spathulenol and germacrene D were the main components accounting for 26.03% and 19.64% of the total EO, respectively. B. hirsuta EO possesses moderate antioxidant activity, both in neutralizing DPPH radicals and in inhibiting β-carotene bleaching. In addition, it exhibits both high antileishmanial activity and selectivity towards the promastigote and amastigote forms. Specifically, B. hirsuta EO showed an IC50 value of 20.78µg/mL and 23.62µg/mL, against the promastigote and amastigote forms of L. infantum, respectively. It also demonstrated an IC50 value of 22.39 and 25.76µg/mL, against the promastigote and amastigote forms of L. major, respectively. However, it exhibited moderate cytotoxicity, with a selectivity index below 10. The investigation of the molecular mechanism of action revealed that B. hirsuta EO inhibited only the sterol pathway, including CYP51 gene expression. Additionally, in silico analysis indicated that the main compounds of B. hirsuta EO, germacrene and spathulenol, exhibited excellent affinity energy against Leishmania enzymes trypanothione reductase (TryR) and trypanothione synthase (TryS). This denotes the potential of these compounds as promising agents to control leishmaniasis.

Effect of Ionizing Radiation on the Activity of the Enzyme Invertase Studied by Polarimetry

The effect of ionizing radiation on biological systems, and particularly the enzymes which are responsible for most cellular functions, leads to chemical alterations in their molecular structure, and as a subsequent result often causes inhibition of their activities. Of particular importance for understanding the molecular and kinetic mechanisms of action of ionizing radiation on these systems is to find suitable experimental protocols and kinetic models applicable to specific enzymes and their substrates. In the present study we offer a convenient experimental approach by applying polarimetric measurements to study the influence of ionizing radiation on the catalytic action of the enzyme invertase. Following the Michaelis- Menten kinetic model we determined the values of the kinetic constants Km и Vmax for the reactions catalyzed either by the native or irradiated invertase and made some conclusions about possible changes either in the active centre or in the molecular structure of the enzyme under the action of ionizing radiation.