1.Zuoguiwan Mitigates Oxidative Stress in Rat Model of Hyperthyroidism Due to Kidney-Yin Deficiency via DRD4/NOX4 Pathway
Ling LIN ; Qianming LIANG ; Changsheng DENG ; Li RU ; Zhiyong XU ; Chao LI ; Mingshun SHEN ; Yueming YUAN ; Muzi LI ; Lei YANG
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(2):43-51
ObjectiveTo decipher the mechanism by which Zuoguiwan (ZGW) treat hyperthyroidism in rats with kidney-Yin deficiency based on the dopamine receptor D4 (DRD4)/nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4) signaling pathway. MethodsThe rat model of kidney-Yin deficiency was induced by unilateral intramuscular injection of dexamethasone (0.35 mg·kg-1). After successful modeling, the rats were randomized into model, methimazole (positive control, 5 mg·kg-1), low-, medium-, and high-dose (1.85, 3.70, 7.40 g·kg-1, respectively) ZGW, and normal control groups. After 21 days of continuous gavage, the behavioral indexes and body weight changes of rats were evaluated. The pathological changes of the renal tissue were observed by hematoxylin-eosin staining. The serum levels of thyroid hormones [triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH)], renal function indexes [serum creatine (Scr) and blood urea nitrogen (BUN)], energy metabolism markers [cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)], and oxidative stress-related factors [superoxide dismutase (SOD), malondialdehyde (MDA), and NADPH)] were measured by enzyme-linked immunosorbent assay (ELISA). Western blot was employed to analyze the expression of DRD4, NOX4, mitochondrial respiratory chain complex proteins [NADH:ubiquinone oxidoreductase subunit S4 (NDUFS4) and cytochrome C oxidase subunit 4 (COX4)], and inflammation-related protein [tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), p38 mitogen-activated protein kinase (MAPK)] pathway in the renal tissue. ResultsCompared with the normal group, the model group showed mental malaise, body weight decreases (P<0.01), inflammatory cell infiltration in the renal tissue, a few residual parotid glands in the thyroid, elevations in serum levels of T3, T4, Scr, BUN, cAMP, cAMP/cGMP, MDA, and NADPH (P<0.01), down-regulation in protein levels of TSH, SOD, and DRD4 (P<0.05, P<0.01), and up-regulation in expression of NOX4, p-p38 MAPK/p38 MAPK, and inflammatory factors (P<0.01). Compared with the model group, ZGW increased the body weight (P<0.05, P<0.01), reduced the infiltration of renal interstitial inflammatory cells, restored the thyroid structure and follicle size, lowered the serum levels of T3, T4, Scr, BUN, cAMP, cAMP/cGMP, MDA and NADPH (P<0.05, P<0.01), up-regulated the expression of TSH, SOD and DRD4 (P<0.05, P<0.01), and down-regulated the expression of NOX4, p-p38 MAPK/p38 MAPK, and inflammatory factors (P<0.05, P<0.01). Moreover, high-dose ZGW outperformed methimazole (P<0.05). ConclusionBy activating DRD4, ZGW can inhibit the expression of NOX4 mediated by the p38 MAPK pathway, reduce oxidative stress and inflammatory response, thereby ameliorating the pathological state of hyperthyroidism due to kidney-Yin deficiency. This study provides new molecular mechanism support for the clinical application of ZGW.
2.Epidemiological characteristics and spatial-temporal aggregation of scarlet fever in Nantong City in 2009 - 2023
Chao BAO ; Junfeng MIAO ; Enhui ZHAO ; Zhenzhen LIU ; Wuhong ZHANG ; Ye WEI
Journal of Public Health and Preventive Medicine 2026;37(2):40-44
Objective To analyze the epidemiological characteristics and spatial-temporal clustering trend of scarlet fever in Nantong from 2009 to 2023, and to provide a scientific basis for scarlet fever prevention and control. Methods The incidence data of scarlet fever in Nantong from 2009 to 2023 were analyzed. Descriptive analysis, seasonal index method and Joinpoint 5.2.0 software were used to analyze epidemiological characteristics. Spatial-temporal clustering was assessed with SaTScan 10.2.5 software. Results The average annual incidence of scarlet fever in Nantong from 2009 to 2023 was 6.54/100 000. The overall morbidity rate of scarlet fever in Nantong had an increasing trend from 2009 to 2019 with an average annual percentage change of 14.55% (t=3.36,P<0.05). The cases mainly occurred during late spring to early summer and late autumn to early winter. Students, preschool children and scattered children were the main scarlet fever population. The average annual incidence of males was significantly higher than that of females (χ2=7.00, P<0.05). Rugao City, Chongchuan District and Tongzhou District were identified as high-incidence areas, accounting for 76.51% of all reported cases. Spatial-temporal scan analysis indicated that Rugao City and Chongchuan District were primary cluster areas, spanning from 2015 to 2021 (RR=3.77, LLR=1 308.07, P<0.05). Conclusion The number of reported cases of scarlet fever in Nantong City from 2009 to 2023 shows epidemic and spatial clustering, mainly concentrated in the central urban area and adjacent counties (cities). It is necessary to strengthen health education and disease surveillance in high-incidence areas, as well as in key institutions and key populations before epidemic peaks.
3.KDM5A/cGAS-STING–mediated microglial activation contributes to prenatal fine particulate matter induced cerebral cortical injury in offspring mice
Wenke NIE ; Li ZHOU ; Siqi WANG ; Chao SONG ; Hang YU ; Wanwei LI ; Mengxiao LUAN ; Lu SUN ; Li YU
Journal of Environmental and Occupational Medicine 2026;43(3):270-277
Background Prenatal exposure to fine particulate matter (PM2.5) is closely associated with cortical damage and neuroinflammation in offspring. The cyclic guanosine monophosphate–adenosine monophosphate synthase (cGAS)–stimulator of interferon genes (STING) signaling pathway is a key regulator of inflammation and may be subject to epigenetic regulation. Objective To investigate the role of cGAS-STING pathway activation in PM2.5-induced cortical damage in offspring mice during pregnancy and the underlying epigenetic regulatory mechanisms. Methods Open field tests were used to assess depressive-like behavior in offspring mice. Morphological analysis was conducted to evaluate cortical damage and microglial activation in offspring brains. Real-time fluorescent quantitative PCR (RT-qPCR) and Western blot (WB) were performed to detect changes in the expression of key molecules in the cGAS-STING pathway in cortical tissue. A PM2.5-induced microglial cell injury model was established in BV2 cells. Microglial activation was observed, cell viability was measured using the Cell Counting Kit-8 (CCK-8), and the expression levels of inducible nitric oxide synthase (iNOS) and key molecules in the cGAS-STING pathway were detected by RT-qPCR and WB. Bioinformatics analysis was performed to explore the epigenetic regulatory association between the STING signaling pathway and lysine-specific demethylase 5A (KDM5A). Changes in KDM5A mRNA and protein expression, as well as the protein level of histone H3 lysine 4 trimethylation (H3K4me3), were detected in an in vitro PM2.5 injury model. Using small interfering RNA (siRNA) technology, the KDM5A gene was silenced in BV2 cells exposed to PM2.5. The protein expression of H3K4me3 was detected to evaluate improvements in microglial activation, changes in inflammatory markers such as iNOS and mannose receptor (CD206), and alterations in the cGAS-STING pathway. Results Compared with the control group, the total distance of offspring mice in the PM2.5 group was significantly reduced, and both the distance traveled and the time spent in the central area of the open field were significantly decreased (P<0.01, P<0.001), indicating depressive-like behavior in the offspring mice. Compared with the control group, the offspring mice in the PM2.5 group exhibited disorganized cortical structure and significantly activated microglia (P<0.01), with significantly increased mRNA and protein levels of cGAS and STING (P<0.05, P<0.01, or P<0.001). The in vitro experiments demonstrated that the PM2.5 treatment induced BV2 cells to polarize toward the M1 phenotype, exhibiting a distinct amoeboid morphology, with upregulated expression of the pro-inflammatory factor iNOS (P<0.05, P<0.01, or P<0.001) and activation of the cGAS-STING pathway (P<0.05, P<0.01). The analysis of RNA-seq data from KDM5A knockout cells revealed significantly downregulated STING expression, suggesting that KDM5A may activate the STING signaling pathway. The in vitro experiments further confirmed that the PM2.5-treated BV2 cells exhibited significantly elevated mRNA and protein levels of KDM5A (P<0.01), while the H3K4me3 protein levels were markedly reduced (P<0.05). After silencing KDM5A in BV2 cells exposed to PM2.5, compared with the PM2.5+siNC group, the PM2.5+siKDM5A group showed no obvious microglial activation and polarized toward the M2 phenotype, with significantly decreased expression levels of iNOS, cluster of differentiation 16 (CD16), and interleukin-1β (P<0.05, P<0.01), and significantly increased expression levels of anti-inflammatory factors CD206, YM1, and interleukin-10 (P<0.01, P<0.001). Meanwhile, the expression levels of cGAS and STING were also reduced (P<0.05, P<0.01). Conclusion KDM5A activates microglia through the cGAS-STING pathway, thereby contributing to PM2.5-induced cortical damage in offspring mice during pregnancy.
4.Immunosuppressive Therapy for Primary Membranous Nephropathy
Medical Journal of Peking Union Medical College Hospital 2026;17(2):301-309
Primary membranous nephropathy (PMN) is a leading cause of nephrotic syndrome in adults. The discovery of antibodies against phospholipase A2 receptor (PLA2R) has ushered in the era of biomarker-based diagnosis and therapeutic monitoring for PMN. The cornerstone of immunosuppressive therapy lies in risk stratification based on proteinuria levels, renal function, and dynamic changes in anti-PLA2R antibody titers, enabling individualized timing of treatment initiation with the dual goals of achieving both immunological and clinical remission. This article systematically reviews the initiation timing, first-line therapeutic options—including cyclophosphamide combined with corticosteroids, calcineurin inhibitors, and anti-CD20 monoclonal antibodies—and key considerations for follow-up and relapse management in PMN, integrating evidence-based findings with clinical practice to inform individualized decision-making.
5.One case of transient bilateral blindness caused by Iodixanol injection and literature review
China Pharmacy 2026;37(7):938-941
OBJECTIVE To explore the characteristics of the transient bilateral blindness caused by Iodixanol injection, analyze its occurrence mechanism, risk factors and treatment strategies, and provide references for the safe clinical use of Iodixanol injection. METHODS A retrospective analysis was conducted on the clinical data of a patient with bilateral vertebral artery stenosis who experienced transient bilateral blindness after receiving Iodixanol injection for interventional treatment. Based on this, combined with relevant literature from both domestic and international sources, a systematic analysis was carried out from aspects such as the correlation of adverse reactions, the mechanism of occurrence, risk factors, clinical characteristics, and treatment measures. RESULTS The patient received approximately 150 mL of Iodixanol injection during the operation. Blurred vision occurred 2 hours after the procedure, which gradually progressed to no light perception in both eyes, accompanied by headache, fever and transient renal dysfunction. According to the criteria for causality assessment of adverse drug reactions, the association between Iodixanol injection and transient bilateral blindness was assessed as “probable”. Combined with analysis of the present case and relevant literature, the underlying mechanisms were speculated to be related to blood-brain barrier disruption, immune reactions and microembolism. Risk factors included underlying cerebrovascular disease, renal insufficiency, high dose of contrast medium and atopic constitution. This adverse reaction was characterized by an acute onset, complex symptoms and obvious reversibility. After symptomatic treatments such as dehydration, anti-allergy therapy, fluid infusion and diuresis, as well as neurotrophic therapy, the patient’s vision recovered completely on the 5th day after surgery, and renal function also returned to the preoperative levels. CONCLUSIONS Transient bilateral blindness induced by Iodixanol injection is rare but clinically severe. At present, its exact pathogenesis has not been fully elucidated, and it involves a variety of risk factors. Before clinical administration, it is necessary to comprehensively evaluate the patient’s underlying diseases, renal function and allergy history; control the dosage of contrast medium during the operation; and closely monitor the patient’s condition after surgery. Once adverse reactions occur, timely intervention should be taken to improve the prognosis.
6.Anti-hepatic Fibrosis Mechanism of Yinqi Sanhuang Jiedu Decoction via Inhibiting Neutrophils and Neutrophil Extracellular Traps
Yanbo LI ; Chao LEI ; Qingjuan WU ; Wenliang LYU
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):103-111
ObjectiveTo verify the therapeutic effect of Yinqi Sanhuang Jiedu decoction (YQSH) on carbon tetrachloride (CCl4)-induced hepatic fibrosis in mice, and to explore whether its effect was related to the inhibition of neutrophil infiltration and the formation of neutrophil extracellular traps (NETs). MethodsThe 36 C57BL/6J mice were randomly divided into control group, model group, positive drug silybin (SF) group (55 mg·kg-1·d-1), YQSH-L group, YQSH-M group, and YQSH-H group (8.325, 16.65, 33.3 g·kg-1·d-1, respectively),n=6 in each group. Except for the control group, mice in all other groups were intraperitoneally injected with CCl4 to induce hepatic fibrosis. After successful modeling, each drug administration group was given the corresponding drugs by gavage for eight weeks. Hematoxylin-eosin (HE) staining, Sirius red staining and Masson staining were used to observe the pathological changes of liver tissue. Liver elasticity was detected by a color Doppler ultrasound system. Immunohistochemistry and real-time fluorescent quantitative polymerase chain reaction (Real-time PCR) were performed to detect the protein expression and mRNA levels of C-X-C motif chemokine ligand 1 (CXCL1), CXCL2 and CXCL5. Neutrophil levels were detected by flow cytometry. The expression of neutrophil elastase (NE) and myeloperoxidase (MPO) positive protein was observed by immunofluorescence. The contents of MPO, NE and CitH3 were detected by enzyme-linked immunosorbent assay (ELISA). ResultsCompared with the control group, the liver of the model group showed obvious inflammatory cell infiltration and collagen deposition, and the liver elasticity, CXCL1, CXCL2, CXCL5 expression, neutrophil level, and MPO, NE and CitH3 levels were significantly increased (P<0.05, P<0.01). Compared with the model group, inflammatory cell infiltration and collagen deposition in the liver tissue of mice were reduced after YQSH treatment. Moreover, the liver elasticity was reduced (P<0.01). The protein expression (P<0.01) and mRNA level of CXCL1, CXCL2 and CXCL5 were decreased(P<0.05,P<0.01). The neutrophil level was decreased (P<0.01), the expression of MPO and NE positive protein was significantly decreased(P<0.05,P<0.01), and the levels of MPO, NE and CitH3 were decreased (P<0.05, P<0.01). ConclusionThe anti-hepatic fibrosis effect of YQSH may be related to its inhibition of chemokines (CXCL1, CXCL2, CXCL5), reduction of neutrophil infiltration, and inhibition of NETs generation.
7.Anti-hepatic Fibrosis Mechanism of Yinqi Sanhuang Jiedu Decoction via Inhibiting Neutrophils and Neutrophil Extracellular Traps
Yanbo LI ; Chao LEI ; Qingjuan WU ; Wenliang LYU
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):103-111
ObjectiveTo verify the therapeutic effect of Yinqi Sanhuang Jiedu decoction (YQSH) on carbon tetrachloride (CCl4)-induced hepatic fibrosis in mice, and to explore whether its effect was related to the inhibition of neutrophil infiltration and the formation of neutrophil extracellular traps (NETs). MethodsThe 36 C57BL/6J mice were randomly divided into control group, model group, positive drug silybin (SF) group (55 mg·kg-1·d-1), YQSH-L group, YQSH-M group, and YQSH-H group (8.325, 16.65, 33.3 g·kg-1·d-1, respectively),n=6 in each group. Except for the control group, mice in all other groups were intraperitoneally injected with CCl4 to induce hepatic fibrosis. After successful modeling, each drug administration group was given the corresponding drugs by gavage for eight weeks. Hematoxylin-eosin (HE) staining, Sirius red staining and Masson staining were used to observe the pathological changes of liver tissue. Liver elasticity was detected by a color Doppler ultrasound system. Immunohistochemistry and real-time fluorescent quantitative polymerase chain reaction (Real-time PCR) were performed to detect the protein expression and mRNA levels of C-X-C motif chemokine ligand 1 (CXCL1), CXCL2 and CXCL5. Neutrophil levels were detected by flow cytometry. The expression of neutrophil elastase (NE) and myeloperoxidase (MPO) positive protein was observed by immunofluorescence. The contents of MPO, NE and CitH3 were detected by enzyme-linked immunosorbent assay (ELISA). ResultsCompared with the control group, the liver of the model group showed obvious inflammatory cell infiltration and collagen deposition, and the liver elasticity, CXCL1, CXCL2, CXCL5 expression, neutrophil level, and MPO, NE and CitH3 levels were significantly increased (P<0.05, P<0.01). Compared with the model group, inflammatory cell infiltration and collagen deposition in the liver tissue of mice were reduced after YQSH treatment. Moreover, the liver elasticity was reduced (P<0.01). The protein expression (P<0.01) and mRNA level of CXCL1, CXCL2 and CXCL5 were decreased(P<0.05,P<0.01). The neutrophil level was decreased (P<0.01), the expression of MPO and NE positive protein was significantly decreased(P<0.05,P<0.01), and the levels of MPO, NE and CitH3 were decreased (P<0.05, P<0.01). ConclusionThe anti-hepatic fibrosis effect of YQSH may be related to its inhibition of chemokines (CXCL1, CXCL2, CXCL5), reduction of neutrophil infiltration, and inhibition of NETs generation.
8.Clinical and genetic analysis of a child with 46,XX male phenotype due to SOX3 gene duplication.
Xiou WANG ; Fuying SONG ; Ziqin LIU ; Pengchao WANG ; Mu DU ; Yi SONG ; Shuyue HUANG ; Bingyan CHAO
Chinese Journal of Medical Genetics 2026;43(1):50-56
OBJECTIVE:
To summarize the clinical and genetic characteristics of a child with 46,XX Ovotesticular disorder of sex development (46,XX OTDSD) due to copy number variation of SOX3 gene.
METHODS:
A 46,XX male patient presented at the Capital Center for Children's Health, Capital Medical University in November 2024 was selected as the study subject. Clinical data of the child was collected. Peripheral blood samples were taken from the child and his parents and subjected to trio whole-genome sequencing. Skewed X-chromosome inactivation was tested in the child and his mother. A literature review was carried out on 46,XX males associated with mutations of the SOX3 gene. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: SHERLL2025056).
RESULTS:
The 10-year-old boy presented with hypospadias and cryptorchidism at birth. Chromosome analysis at one year and a half revealed a 46,XX karyotype. Gonadal biopsy showed testicular tissue, while ultrasound at the age of 10 detected ovotesticular tissue. Whole-genome sequencing identified a 660 kb duplication in the Xq27.1 region, which was derived from his mother. X-chromosome inactivation testing showed random inactivation in the child and mild non-random inactivation in the mother. Literature review has found 11 publications involving 15 patients (including our case), among whom 14 had a male social gender. They had primarily presented with hypospadias at birth but had no significant endocrine abnormalities. Most patients had experienced testicular failure after puberty. SOX3 related 46,XX males are mainly caused by de novo duplications, although a few maternal carriers had been discovered.
CONCLUSION
Duplication of the SOX3 gene probably underlay the pathogenesis is this 46,XX male. Individuals with 46,XX SRY negative male phenotypes should be routinely screened for SOX3 gene variants. Structural variations of the SOX3 gene can lead to complete or partial sex reversal in 46,XX individuals with minimal impact on intellectual and motor development, as well as other endocrine hormones.
Child
;
Humans
;
Male
;
46, XX Disorders of Sex Development/genetics*
;
DNA Copy Number Variations
;
Gene Duplication
;
Phenotype
;
SOXB1 Transcription Factors/genetics*
9.Exploring Mechanism of Chaihu Jia Longgu Mulitang in Depressive-like Rats via AMPK/SIRT1/NF-κB/NLRP3 Signaling Pathway
Guang WANG ; Xinhua SONG ; Jie YANG ; Jinyao XU ; Junhua MEI ; Chao CHEN ; Guohua CHEN
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(11):144-152
ObjectiveTo investigate the effects of Chaihu Jia Longgu Mulitang(CJLM) on depression-like behaviors and neuroinflammation in rats subjected to social isolation combined with chronic unpredictable mild stress(CUMS), and to explore the potential underlying mechanisms. MethodsSixty male SD rats were randomly divided into a normal group, a model group, and low-, medium-, and high-dose CJLM groups(2.89, 5.78, 11.56 g·kg-1), as well as a fluoxetine group(10 mg·kg-1). Except for the normal group, all other groups were subjected to social isolation combined with CUMS for 63 d. During the first 35 d, depression models were established only, and from day 36 onward, modeling and drug administration were conducted simultaneously for a total intervention period of 28 d. Depression-like behaviors were evaluated using the sucrose preference test, open-field test, and forced swimming test. Hematoxylin-eosin(HE) staining was performed to observe hippocampal histomorphology. Immunohistochemistry(IHC) was used to detect the expression levels of ionized calcium-binding adapter molecule 1(Iba1) and gasdermin D(GSDMD) proteins in the hippocampus. Western blot analysis was employed to determine the protein expression levels of adenosine 5′-monophosphate(AMP)-activated protein kinase(AMPK) and phosphorylated(p)-AMPK, silent information regulator 1(SIRT1), nuclear factor-κB(NF-κB) and p-NF-κB, NOD-like receptor protein 3(NLRP3), and Caspase-1 in the hippocampus. Real-time quantitative polymerase chain reaction(Real-time PCR) was used to detect the mRNA expression levels of tumor necrosis factor-α(TNF-α), interleukin(IL)-6, and IL-1β in the hippocampus. ResultsCompared with the normal group, the model group showed a decreased sucrose preference rate(P<0.01), reduced total movement distance(P<0.01), prolonged immobility time(P<0.01), and decreased central zone residence time(P<0.01) in the open-field test, and increased immobility time in the forced swimming test(P<0.01). Hippocampal neuronal structure was damaged. The contents of Iba1 and GSDMD in the hippocampus were significantly increased(P<0.01). The protein expression levels of p-AMPK and SIRT1 in the hippocampus were significantly decreased(P<0.01), whereas the protein expression levels of p-NF-κB, NLRP3, and Caspase-1 were significantly increased(P<0.01). The mRNA expression levels of IL-1β, IL-6, and TNF-α in the hippocampus were significantly upregulated(P<0.01). Compared with the model group, the low-, medium-, and high-dose CJLM groups and the fluoxetine group all were able to reverse depression-like behavioral changes, as evidenced by increased sucrose preference rate, increased total movement distance with shortened immobility time in the open-field test, prolonged central zone residence time, and reduced immobility time in the forced swimming test(P<0.05, P<0.01). Meanwhile, hippocampal neuronal structural damage was alleviated. In the hippocampus, the expression levels of Iba1 and GSDMD were downregulated, the expression levels of p-AMPK and SIRT1 were upregulated, and the abnormal elevations of p-NF-κB, NLRP3, Caspase-1, as well as IL-1β, IL-6, and TNF-α mRNA were suppressed(P<0.05, P<0.01). ConclusionCJLM can ameliorate depression-like behaviors in rats subjected to social isolation combined with CUMS and attenuate hippocampal neuroinflammation and pyroptosis, suggesting that its effects may be associated with the regulation of AMPK/SIRT1/NF-κB/NLRP3 signaling pathway.
10.Study on the interaction between small molecule Lyb24 and dihydroorotate dehydrogenase PyrD
Jiarong SUN ; Shuyan WANG ; Wei HUANG ; Chao LU
Journal of China Pharmaceutical University 2026;57(2):240-245
This study aimed to explore the interaction between the small molecule Lyb24 and PyrD, a key enzyme in the pyrimidine biosynthesis pathway of Klebsiella pneumoniae (KP), and the effect of Lyb24 on the catalytic activity of PyrD, thus to provide a theoretical basis for the development of novel antimicrobial agents. The pET-30a(+)-PyrD recombinant plasmid was constructed using Nde I/Xba I double digestion technology and was transformed into Escherichia coli BL21 (DE3) competent cells using the heat-shock method. The recombinant protein was induced at 16 ℃ with 0.3 mmol/L isopropyl β-D-thiogalactopyranoside (IPTG). The recombinant PyrD protein was purified using nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography to obtain a high-purity product. Surface plasmon resonance (SPR) experiments were conducted to detect the direct interaction between Lyb24 and PyrD protein, and a DCIP-based colorimetric assay was used to evaluate the effect of Lyb24 on the catalytic activity of PyrD. The pET-30a(+)-PyrD plasmid was successfully constructed, and the recombinant PyrD protein with a molecular weight of approximately 36 kD was expressed and purified to a concentration of 5.58 mg/mL. Lyb24 exhibited high-affinity direct binding to PyrD (KD = 8.83 × 10−5 mol/L) and exerted an uncompetitive inhibition effect on the catalytic activity of PyrD. This study demonstrates that Lyb24, a small-molecule compound, directly binds to PyrD and inhibits its enzymatic activity, providing crucial experimental evidence for developing PyrD-targeted antibacterial agents with value of clinical translation.


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