Ultrathin Cu9S5 Nanosheets with Sulfur Vacancy for Multimodal Tumor Therapy.

Multimodal tumor therapy with nanotechnology is an effective and integrative strategy to overcome the limitations of therapeutic efficacy and possible side effects associated with monotherapy. However, the construction of multimodal treatment nanoplatforms often involves various functional components, leading to certain challenges, such as time-consuming synthesis processes, low product yield, and inadequate biocompatibility. To address these issues, we have developed a straightforward method for preparing ultrathin Cu9S5 nanosheets (NSs) with surface defects for photothermal/photodynamic/chemodynamic therapy. The ultrathin morphology of the Cu9S5 NSs (with 2-3 nm) not only confers excellent biocompatibility but also enables broad-spectrum absorption with a remarkable photothermal conversion efficiency (58.96%) under 1064 nm laser irradiation. Moreover, due to the presence of a S vacancy, these Cu9S5 NSs exhibit favorable enzyme-like properties, including reactive oxygen species generation and glutathione consumption, particularly under laser irradiation. The efficacy of related tumor therapy and antibacterial treatment is significantly enhanced by the synergistic activation of photothermal/photodynamic/chemodynamic therapy through 1064 nm laser irradiation, as demonstrated by both in vitro and in vivo experiments. This study presents a novel strategy for multimodal tumor therapy with the prepared ultrathin Cu9S5 NSs, which holds promising pathways for photodynamic therapy in the NIR-II region.

Self-Assembly of a Linear-Dendritic Polymer Containing Cisplatin and Norcantharidin into Raspberry-like Multimicelle Clusters for the Efficient Chemotherapy of Liver Cancer.

Combination chemotherapy has been proved to be an effective strategy in the clinic, and nanoformulations have drawn much attention in the field of drug delivery. However, conventional nanocarriers suffer from shortcomings such as inefficient coloading and undesired molar ratios of the combined drugs, preleakage of cargos during systemic circulation, and lack of cancer-selective drug release. To achieve tumor-specific codelivery of cisplatin (CDDP) and norcantharidin (NCTD) for synergistic treatment of liver cancer, a novel linear-dendritic polymer, termed as G1(PPDC)x, was designed and synthesized, where a prodrug consisting of cisplatin (CDDP) and norcantharidin (NCTD) was conjugated to PEG2000 via ester bonds to fabricate linear polymer-drug conjugates, and the conjugates were subsequently grafted to the terminal hydroxyls of a dendritic polycarbonate core. Benefiting from the hydrogen bond interactions, G1(PPDC)x could spontaneously self-assemble into a unique type of raspberry-like multimicelle clusters in solution (G1(PPDC)x-PMs). G1(PPDC)x-PMs possessed an optimal synergistic ratio of CDDP and NCTD, without obvious premature release or disassembly in biological environments. Intriguingly, upon extravasation into the interstitial tumor tissues, G1(PPDC)x-PMs (132 nm in diameter) could disassemble and reassemble into smaller micelles (40 nm in diameter) in response to the mildly acidic tumor microenvironment, which would enhance the deep tumor penetration and cellular accumulation of drugs. In vivo delivery of G1(PPDC)x-PMs led to a significantly prolonged blood circulation half-life, which is beneficial to achieve sufficient tumor accumulation through the enhanced permeability and retention (EPR) effect. G1(PPDC)x-PMs displayed the best antitumor activity in H22 tumor-bearing mice with a tumor inhibition rate of 78.87%. Meanwhile, G1(PPDC)x-PMs alleviated both myelosuppression toxicities of CDDP and vascular irritation of NCTD. Our results demonstrated that G1(PPDC)x-PMs could serve as an effective drug delivery system for codelivery of CDDP and NCTD to treat liver cancer efficiently.

Synergistic Antibacterial Activity of Benzalkonium Bromide and Cu-Bearing Duplex Stainless Steel against Pseudomonas aeruginosa.

The bactericide benzalkonium bromide is widely used to kill Pseudomonas aeruginosa, which causes microbiologically influenced corrosion (MIC). However, the extensive use of benzalkonium bromide will enhance bacterial drug resistance and cause environmental pollution. In this study, benzalkonium bromide combined with Cu-bearing 2205 duplex stainless steel (2205-Cu DSS) was used to kill Pseudomonas aeruginosa; the germicidal rate of the combination of benzalkonium bromide and 2205-Cu DSS was 24.2% higher than that of using benzalkonium bromide alone, after five days. The antibacterial efficacy was evaluated using an antibacterial test and biofilm observation. The results showed that, in the presence of P. aeruginosa, the combination of 23.44 ppm benzalkonium bromide and 2205-Cu DSS showed the best antibacterial efficacy.

[Sleep deprivation aggravates cognitive impairment in septic rats by activating neuronal glycolytic isoenzyme PFKFB3].

OBJECTIVE: To evaluate the effect of sleep deprivation on cognitive function in septic rats and its relationship with neuronal glycolysis isoenzyme phosphofructokinase-2/fructose-2, 6-diphosphatase 3 (PFKFB3). METHODS: Fifty-six healthy male Sprague-Dawley (SD) rats were randomly divided into 4 groups (n = 14): control group (Con group), sepsis group (LPS group), sepsis+sleep deprivation group (LPS+SD group), sepsis+sleep deprivation+glycolysis inhibitor 3-PO treatment group (LPS+SD+3-PO group). The sepsis model was established by intraperitoneal injection of lipopolysaccharide (LPS) 10 mg/kg. Rats in LPS+SD group were treated with sleep deprivation using a sleep deprivation instrument 24 hours after LPS injection. The LPS+SD+3-PO group was intraperitoneally injected with LPS for 24 hours, and then injected with 3-PO 50 mg/kg, followed by sleep deprivation. Novel object recognition experiments were performed 72 hours after LPS injection. Subsequently, blood and brain tissue samples were collected. The contents of lactate (Lac), reactive oxygen species (ROS) and serum tumor necrosis factor-α (TNF-α), neuron-specific enolase (NSE), pyruvate in brain tissue were detected by enzyme-linked immunosorbent assay (ELISA). Then, the lactate/pyruvate ratio was calculated. Na+-K+-ATPase activity in brain tissue was detected by colorimetry. Morphological changes in hippocampus were detected by hematoxylin-eosin (HE) staining. And the protein expression levels of PFKFB3, ZO-1 and cleaved caspase-3 were measured by Western blotting. RESULTS: Compared with Con group, the novel object recognition index of LPS group was decreased, the levels of NSE, TNF-α, lactate/pyruvate ratio in serum and the levels of Lac, ROS and dry-wet weight ratio in brain tissue were significantly increased, Na+-K+-ATPase activity in brain tissue was decreased, the protein expressions of PFKFB3, caspase-3 were up-regulated, ZO-1 expression was down-regulated, and the neurons in hippocampus were slightly degenerated. Compared with LPS group, the novel object recognition index of LPS+SD group was further decreased [(39.4±5.3)% vs. (54.5±7.6)%)], serum NSE, TNF-α, lactate/pyruvate ratio and brain tissue Lac, ROS, dry-wet weight ratio were further increased [NSE (µg/L): 3.21±0.42 vs. 2.55±0.36, TNF-α (ng/L): 139.4±19.7 vs. 92.2±13.5, lactate/pyruvate ratio: 29.7±5.5 vs. 19.2±4.2, Lac (µmol/g): 19.51±2.33 vs. 11.34±1.52, ROS (kU/g): 117.4±18.7 vs. 78.2±11.8, dry-wet weight ratio: (81.3±9.2)% vs. (64.3±6.6)%], and Na+-K+-ATPase activity was further decreased (mmol×L-1×h-1: 1.88±0.34 vs. 2.91±0.39), the protein expressions of PFKFB3, caspase-3 were further up-regulated and ZO-1 expression was further down-regulated (PFKFB3/ß-actin: 0.80±0.11 vs. 0.45±0.07, caspase-3/ß-actin: 0.71±0.09 vs. 0.37±0.05, ZO-1/ß-actin: 0.31±0.05 vs. 0.61±0.08). The differences were statistically significant (all P < 0.05). HE staining showed that the degeneration of neurons in hippocampus was significantly aggravated. Compared with LPS+SD group, the novel object recognition index of LPS+SD+3-PO group was increased [(50.8±5.9)% vs. (39.4±5.3)%], NSE, TNF-α, lactate/pyruvate ratio of serum and Lac, ROS, dry-wet weight ratio of brain tissue were significantly decreased [NSE (µg/L): 2.60±0.33 vs. 3.21±0.42, TNF-α (ng/L): 103.7±18.3 vs. 139.4±19.7, lactate/pyruvate ratio: 17.4±5.1 vs. 29.7±5.5, Lac (µmol/g): 13.68±2.02 vs. 19.51±2.33, ROS (kU/g): 86.9±14.5 vs. 117.4±18.7, dry-wet weight ratio: (67.7±6.9)% vs. (81.3±9.2)%], and Na+-K+-ATPase activity was increased (mmol×L-1×h-1: 2.82±0.44 vs. 1.88±0.34). The protein expressions of PFKFB3, caspase-3 were down-regulated and ZO-1 expression was up-regulated (PFKFB3/ß-actin: 0.50±0.06 vs. 0.80±0.11, caspase-3/ß-actin: 0.43±0.06 vs. 0.71±0.09, ZO-1/ß-actin: 0.52±0.06 vs. 0.31±0.05). The differences were statistically significant (all P < 0.05). HE staining showed that the degeneration of neurons in hippocampus was significantly improved. CONCLUSIONS: Sleep deprivation could aggravate neuroinflammation, neuronal degeneration and apoptosis in septic rats, resulting in destruction of blood-brain barrier and cognitive impairment. 3-PO treatment significantly alleviate the injury and degeneration of hippocampal neurons in septic rats, inhibit neuroinflammation and apoptosis, and improve cognitive dysfunction, which may be related to the inhibition of glycolytic isoenzyme PFKFB3.

Au nanocluster-modulated macrophage polarization and synoviocyte apoptosis for enhanced rheumatoid arthritis treatment.

The persistent progression of synovial inflammation and cartilage destruction contributes to the crosstalk between pro-inflammatory macrophages and activated fibroblast-like synoviocytes (FLSs) in a synovial microenvironment. In this work, structurally well-defined Au25 nanoclusters were synthesized to induce phenotypic polarization of pro-inflammatory macrophages and apoptosis of activated FLSs for enhanced rheumatoid arthritis treatment. These ultra-small nanoclusters significantly modulated phenotypic polarization of a pro-inflammatory M1 phenotype to an anti-inflammatory phenotype M2 for relieving inflammation. Additionally, Au25 nanoclusters can efficiently activate reactive oxygen species (ROS)-mediated apoptotic signaling pathways by inactivating thioredoxin reductase (TrxR), resulting in imbalance of the cellular redox homeostasis and initiation of FLS apoptosis. In an adjuvant-induced arthritis rat model, Au25 nanoclusters efficiently ameliorated the hyperplasia of the synovium and reduced inflammatory cell infiltration with negligible side effects. This study provided a new insight into Au nanoclusters for treating rheumatoid arthritis.

BmK DKK13, A Scorpion Toxin, Alleviates Pain Behavior in a Rat Model of Trigeminal Neuralgia by Modulating Voltage-Gated Sodium Channels and MAPKs/CREB Pathway.

BmK DKK13 (DKK13) is a mutated recombinant peptide, which has a significant antinociception in a rat model of the inflammatory pain. The purpose of this study was to evaluate the antinociceptive effect of DKK13 on trigeminal neuralgia (TN) in rats. Male Sprague-Dawley (SD) rats were treated with the chronic constriction injury of the infraorbital nerve (IoN-CCI) model to induce stable symptoms of TN. DKK13 (1.0 mg/kg, 2.0 mg/kg and 4.0 mg/kg, i.v.) or morphine (4.0 mg/kg, i.v.) was administered by tail vein once on day 14 after IoN-CCI injury. Behavioral tests, electrophysiology and western blotting were performed to investigate the role and underlying mechanisms of DKK13 on IoN-CCI model. Behavioral test results showed that DKK13 could significantly increase the mechanical pain and thermal radiation pain thresholds of IoN-CCI rats and inhibit the asymmetric spontaneous pain scratching behavior. Electrophysiological results showed that DKK13 could significantly reduce the current density of Nav1.8 in the ipsilateral side of trigeminal ganglion (TG) neurons in IoN-CCI rats, and the steady-state activation and inactivation curves of Nav1.8 shifted, respectively, to the direction of hyperpolarization and depolarization. Western blotting results showed that DKK13 significantly reduced the expression of Nav1.8 and the phosphorylation levels of key proteins of MAPKs/CREB pathway in TG tissues of IoN-CCI rats. In brief, DKK13 has a significant antinociceptive effect on IoN-CCI rats, which may be achieved by changing the dynamic characteristics of Nav1.8 channel and regulating the protein phosphorylation in MAPKs/CREB pathway.

Exploring the Pivotal Components Influencing the Side Effects Induced by an Analgesic-Antitumor Peptide from Scorpion Venom on Human Voltage-Gated Sodium Channels 1.4 and 1.5 through Computational Simulation.

Voltage-gated sodium channels (VGSCs, or Nav) are important determinants of action potential generation and propagation. Efforts are underway to develop medicines targeting different channel subtypes for the treatment of related channelopathies. However, a high degree of conservation across its nine subtypes could lead to the off-target adverse effects on skeletal and cardiac muscles due to acting on primary skeletal muscle sodium channel Nav1.4 and cardiac muscle sodium channel Nav1.5, respectively. For a long evolutionary process, some peptide toxins from venoms have been found to be highly potent yet selective on ion channel subtypes and, therefore, hold the promising potential to be developed into therapeutic agents. In this research, all-atom molecular dynamic methods were used to elucidate the selective mechanisms of an analgesic-antitumor ß-scorpion toxin (AGAP) with human Nav1.4 and Nav1.5 in order to unravel the primary reason for the production of its adverse reactions on the skeletal and cardiac muscles. Our results suggest that the rational distribution of residues with ring structures near position 38 and positive residues in the C-terminal on AGAP are critical factors to ensure its analgesic efficacy. Moreover, the substitution for residues with benzene is beneficial to reduce its side effects.

Study of Anti-Inflammatory and Analgesic Activity of Scorpion Toxins DKK-SP1/2 from Scorpion Buthus martensii Karsch (BmK).

Buthus martensii Karsch (BmK), is a kind of traditional Chinese medicine, which has been used for a long history for the treatment of many diseases, such as inflammation, pain and cancer. In this study, DKK-SP1/2/3 genes were screened and extracted from the cDNA library of BmK. The DKK-SP1/2/3 were expressed by using plasmid pSYPU-1b in E. coli BL21, and recombinant proteins were obtained by column chromatography. In the xylene-induced mouse ear swelling and carrageenan-induced rat paw swelling model, DKK-SP1 exerted a significant anti-inflammatory effect by inhibiting the expression of Nav1.8 channel. Meanwhile, the release of pro-inflammatory cytokines (COX-2, IL-6) was decreased significantly and the release of anti-inflammatory cytokines (IL-10) were elevated significantly. Moreover, DKK-SP1 could significantly decrease the Nav1.8 current in acutely isolated rat DRG neurons. In the acetic acid-writhing and ION-CCI model, DKK-SP2 displayed significant analgesic activity by inhibiting the expression of the Nav1.7 channel. Moreover, DKK-SP2 could significantly inhibit the Nav1.7 current in the hNav1.7-CHO cells.

N58A Exerts Analgesic Effect on Trigeminal Neuralgia by Regulating the MAPK Pathway and Tetrodotoxin-Resistant Sodium Channel.

The primary studies have shown that scorpion analgesic peptide N58A has a significant effect on voltage-gated sodium channels (VGSCs) and plays an important role in neuropathic pain. The purpose of this study was to investigate the analgesic effect of N58A on trigeminal neuralgia (TN) and its possible mechanism. The results showed that N58A could significantly increase the threshold of mechanical pain and thermal pain and inhibit the spontaneous asymmetric scratching behavior of rats. Western blotting results showed that N58A could significantly reduce the protein phosphorylation level of ERK1/2, P38, JNK, and ERK5/CREB pathways and the expression of Nav1.8 and Nav1.9 proteins in a dose-dependent manner. The changes in current and kinetic characteristics of Nav1.8 and Nav1.9 channels in TG neurons were detected by the whole-cell patch clamp technique. The results showed that N58A significantly decreased the current density of Nav1.8 and Nav1.9 in model rats, and shifted the activation curve to hyperpolarization and the inactivation curve to depolarization. In conclusion, the analgesic effect of N58A on the chronic constriction injury of the infraorbital (IoN-CCI) model rats may be closely related to the regulation of the MAPK pathway and Nav1.8 and Nav1.9 sodium channels.

Potential microRNA panel for the diagnosis and prediction of overall survival of hepatocellular carcinoma with hepatitis B virus infection.

BACKGROUND: In hepatocellular carcinoma (HCC), abnormal expression of multiple microRNAs (miRNAs) has been shown to be involved in the malignant biological behavior of liver cancer. The vast majority of liver cancer cases in China are closely related to hepatitis B virus (HBV) infection, but there are few studies on the changes of miRNA expression in the progression from HBV infection to hepatoma. AIM: To explore the role of miRNAs in the progression of HBV infection to cirrhosis and even to liver cancer. METHODS: We screened differentially expressed miRNAs in 40 HBV cirrhosis, 40 normal and 15 HCC tissues by using a TaqMan Low Density Array and real time quantitative polymerase chain reaction. To evaluate the power of the selected miRNAs to predict disease, we calculated the area under the receiver-operating-characteristic curves. The overall survival of HBV cirrhosis patients was analyzed via Kaplan-Meier analysis. RESULTS: The levels of miR-375, miR-122 and miR-143 were significantly lower in HBV cirrhosis tissues, while miR-224 was significantly higher than in the controls (P < 0.0001). The area under the curves of the receiver-operating-characteristic curve for the 4-miRNA panel was 0.991 (95%CI: 0.974-1). Patients with a lower expression level of miR-224 or higher expression levels of miR-375, miR-122 and miR-143 had longer overall survival. CONCLUSION: The four miRNAs (miR-375, miR-122, miR-143 and miR-224) may be helpful for early diagnosis of HBV infection, HBV cirrhosis, and prediction of its overall survival.

Insights into the binding mode and functional components of the analgesic-antitumour peptide from Buthus martensii Karsch to human voltage-gated sodium channel 1.7 based on dynamic simulation analysis.

Voltage-gated sodium (Nav) channels are transmembrane proteins composed of four homologous domains (DI-DIV) that play important roles in membrane excitability in neurons and muscles. Analgesic-antitumour peptide (AGAP) is a neurotoxin from the scorpion Buthus martensii Karsch, and has been shown to exert analgesic effect by binding on site 4 of human Nav1.7 (hNav1.7). Mechanistic details about this binding, however, remain unclear. To address this issue, we compared the binding modes of AGAP/AGAPW38G/AGAPW38F and the hNav1.7 voltage-sensing domain on DII (VSD2hNav1.7) using homology modeling, molecular docking, molecular dynamics simulation and steered molecular dynamics. Results revealed the key role of tryptophan at position 38 on the binding of AGAP to VSD2hNav1.7. Pivotal roles are played also by residues on the ß-turn and negatively charged residues at the C-terminal. We further show that electrostatic interaction is the main contributor to the binding free energy of the complex. Agreement between our computational simulation findings and prior experimental data supports the accuracy of the described mechanism. Accordingly, these results can provide valuable information for designing potent toxin analgesics targeting hNav1.7 with high affinity.Communicated by Ramaswamy H. Sarma.

Anti-Nociceptive and Anti-Inflammation Effect Mechanisms of Mutants of Syb-prII, a Recombinant Neurotoxic Polypeptide.

Syb-prII, a recombinant neurotoxic polypeptide, has analgesic effects with medicinal value. Previous experiments indicated that Syb-prII displayed strong analgesic activities. Therefore, a series of in vivo and vitro experiments were designed to investigate the analgesic and anti-inflammatory properties and possible mechanisms of Syb-prII. The results showed that administered Syb-prII-1 and Syb-prII-2 (0.5, 1, 2.0 mg/kg, i.v.) to mice significantly reduced the time of licking, biting, or flicking of paws in two phases in formalin-induced inflammatory nociception. Syb-prII-1 inhibited xylene-induced auricular swelling in a dose-dependent manner. The inhibitory effect of 2.0 mg/kg Syb-prII-1 on the ear swelling model was comparable to that of 200 mg/kg aspirin. In addition, the ELISA and Western blot analysis suggested that Syb-prII-1 and Syb-prII-2 may exert an analgesic effect by inhibiting the expression of Nav1.8 and the phosphorylation of ERK, JNK, and P38. Syb-prII-1 markedly suppressed the expression of IL-1ß, IL-6, and TNF-α of mice in formalin-induced inflammatory nociception. We used the patch-clamp technique and investigated the effect of Syb-prII-1 on TTX-resistant sodium channel currents in acutely isolated rat DRG neurons. The results showed that Syb-prII-1 can significantly down regulate TTX-resistant sodium channel currents. In conclusion, Syb-prII mutants may alleviate inflammatory pain by significantly inhibiting the expression of Nav1.8, mediated by the phosphorylation of MAPKs and significant inhibition of TTX-resistant sodium channel currents.

Enantioseparation and molecular modeling study of five ß-adrenergic blockers on Chiralpak IC column.

A new high-performance liquid chromatography (HPLC) method was developed for the enantiomeric resolution of five ß-adrenergic blockers on a Chiralpak IC column (250 mm × 4.6 mm, 5.0 µm particle size) in normal phase mode. The mobile phase used was n-hexane-ethanol-diethylamine in different proportions at the flow rate of 1.0 mL/min with the column temperature of 25°C using a UV detector at 230 nm. The influences of base additives and alcohol modifiers were evaluated and optimized. The maximum resolution values for bevantolol, propranolol carteolol, esmolol, and metoprolol were 4.80, 2.77, 2.09, 2.30, and 1.11, respectively. To gain a better understanding of the interaction between chiral stationary phase and analyte enantiomers, the molecular docking of chiral stationary phase with five pairs of enantiomer was carried out using AutoDock molecular docking technique. By simulation studies, the mechanism of chiral recognition was determined. According to the results, hydrogen bond interactions and π-π interactions were the chief interactions for the chiral recognition.

Tumor-Suppressive Function of miR-30d-5p in Prostate Cancer Cell Proliferation and Migration by Targeting NT5E.

MiR-30d-5p, a member of the microRNA family, was recently reported to regulate androgen receptor signaling in prostate cancer (PCa). Ecto-5'-nucleotidase (NT5E/CD73) is a pivotal regulator of tumor migration and has angiogenetic properties. However, the undiscovered function of miR-30d-5p and whether it targeted NT5E in PCa remain uncertain. In this study, the authors observed miR-30d-5p was significantly downregulated in PCa tissues and cell lines compared with the adjacent normal tissues and normal prostate cells, respectively. The lower expression of miR-30d-5p was found to be inversely correlated with the NT5E expression in PCa tissues. Subsequently, the biological function of miR-30d-5p was evaluated in PCa in vitro. The results indicated that miR-30d-5p overexpression inhibited PCa cell growth and invasion by MTT, Transwell assays, respectively, as well as induced cell cycle G0/G1 phase arrest and apoptosis using flow cytometry analysis. In addition, miR-30d-5p directly bound to the 3'UTR (3' untranslated region) of NT5E in DU-145 and PC-3 cells by luciferase reporter assay. Furthermore, enforced NT5E expression alleviated miR-30d-5p inhibition of PCa cell growth and invasion in DU145 cells. Taken together, these data indicated that miR-30d-5p may be a potential therapeutic target for the treatment of PCa by serving as a tumor suppressor, by negatively regulating NT5E.

A mutant of the Buthus martensii Karsch antitumor-analgesic peptide exhibits reduced inhibition to hNav1.4 and hNav1.5 channels while retaining analgesic activity.

Scorpion toxins can kill other animals by inducing paralysis and arrhythmia, which limits the potential applications of these agents in the clinical management of diseases. Antitumor-analgesic peptide (AGAP), purified from Buthus martensii Karsch, has been proved to possess analgesic and antitumor activities. Trp38, a conserved aromatic residue of AGAP, might play an important role in mediating AGAP activities according to the sequence and homology-modeling analyses. Therefore, an AGAP mutant, W38G, was generated, and effects of both AGAP and the mutant W38G were examined by whole-cell patch clamp techniques on the sodium channels hNav1.4 and hNav1.5, which were closely associated with the biotoxicity of skeletal and cardiac muscles, respectively. The data showed that both W38G and AGAP inhibited the peak currents of hNav1.4 and hNav1.5; however, W38G induced a much weaker inhibition of both channels than AGAP. Accordingly, W38G exhibited much less toxic effect on both skeletal and cardiac muscles than AGAP in vivo The analgesic activity of W38G and AGAP were verified in vivo as well, and W38G retained analgesic activity similar to AGAP. Inhibition to both Nav1.7 and Nav1.8 was involved in the analgesic mechanism of AGAP and W38G. These findings indicated that Trp38 was a key amino acid involved in the biotoxicity of AGAP, and the AGAP mutant W38G might be a safer alternative for clinical application because it retains the analgesic efficacy with less toxicity to skeletal and cardiac muscles.

Molecular "surgery" on a 23-gold-atom nanoparticle.

Compared to molecular chemistry, nanochemistry is still far from being capable of tailoring particle structure and functionality at an atomic level. Numerous effective methodologies that can precisely tailor specific groups in organic molecules without altering the major carbon bones have been developed, but for nanoparticles, it is still extremely difficult to realize the atomic-level tailoring of specific sites in a particle without changing the structure of other parts (for example, replacing specific surface motifs and deleting one or two metal atoms). This issue severely limits nanochemists from knowing how different motifs in a nanoparticle contribute to its overall properties. We demonstrate a site-specific "surgery" on the surface motif of an atomically precise 23-gold-atom [Au23(SR)16]- nanoparticle by a two-step metal-exchange method, which leads to the "resection" of two surface gold atoms and the formation of a new 21-gold-atom nanoparticle, [Au21(SR)12(Ph2PCH2PPh2)2]+, without changing the other parts of the starting nanoparticle structure. This precise surgery of the nanocluster reveals the different reactivity of the surface motifs and the inner core: the least effect of surface motifs on optical absorption but a distinct effect on photoluminescence (that is, a 10-fold enhancement of luminescence after the tailoring). First-principles calculations further reveal the thermodynamically preferred reaction pathway for the formation of [Au21(SR)12(Ph2PCH2PPh2)2]+. This work constitutes a major step toward the development of atomically precise, versatile nanochemistry for the precise tailoring of the nanocluster structure to control its properties.

Distinct structural changes in wild-type and amyloidogenic chicken cystatin caused by disruption of C95-C115 disulfide bond.

Human cystatin C (HCC) amyloid angiopathy (HCCAA) is characterized by tissue deposition of amyloid fibrils in blood vessels, which can lead to recurrent hemorrhagic stroke. Wild-type HCC forms part of the amyloid deposits in brain arteries of elderly people with amyloid angiopathy. A point mutation causing a glutamine to a leucine substitution at residue 68 in the HCC polypeptide chain greatly increases the amyloidogenic propensity of HCC and causes a more severe cerebral hemorrhage and premature death in young adults. In this study, we used molecular dynamics simulations to assess the importance of disulfide bridge formation upon the stability of chicken cystatin and how this may influence the propensity for amyloid formation. We found that disulfide bridge formation between Cys95 and Cys115 in human cystatin played a critical role in overall protein stability. Importantly, Cys95-Cys115 influenced cystatin structure in regions of the protein that play key roles in the protein-folding transitions that occur, which enable amyloid fibril formation. We hypothesized that correct disulfide bridge formation is a critical step in stabilizing cystatin toward its native conformation. Disrupting Cys95-Cys115 disulfide bridge formation within cystatin appears to significantly enhance the amyloidogenic properties of this protein. In addition, by combining in silico studies with our previous experimental results on Eps1, a molecular chaperone of the PDI family, we proposed that age-related HCCAA, may possess a different pathogenic mechanism compared with its amyloidogenic counterpart, the early onset amyloidogenic cystatin-related CAA.

Site-directed mutagenesis of BmK AGP-SYPU1: the role of two conserved Tyr (Tyr5 and Tyr42) in analgesic activity.

In this study, the role of two conversed tyrosines (Tyr5 and Tyr42) from the scorpion toxin BmK AGP-SYPU1 was investigated with an effective Escherichia coli expression system. Site-directed mutagenesis was used to individually substitute Tyr5 and Tyr42 with hydrophobic or hydrophilic amino acids, and the extent to which these scorpion toxin BmK AGP-SYPU1 tyrosines contribute to analgesic activity was evaluated. The results of the mouse-twisting test showed that Tyr5 and Tyr42 are associated with the analgesic activity of the toxin because the analgesic activities of Y5F and Y42F were significantly increased compared with the rBmK AGP-SYPU1; however, the Y5W had decreased activity. The results of molecular simulation reveal the following: (1) for analgesic activity, the core domain of the scorpion toxin BmK AGP-SYPU1 is key and (2) for pharmacological function, Tyr42 is most likely involved when the core domain conformation is altered. These studies identify a new relationship between the structure and analgesic activity of the scorpion toxin BmK AGP-SYPU1 and are significant for further research and the application of analgesic peptides.

The role of glycine residues at the C-terminal peptide segment in antinociceptive activity: a molecular dynamics simulation.

Elucidating structural determinants in the functional regions of toxins can provide useful knowledge for designing novel analgesic peptides. Glycine residues at the C-terminal region of the neurotoxin BmK AGP-SYPU2 from the scorpion Buthus martensii Karsch (BmK) have been shown to be crucial to its analgesic activity. However, there has been no research on the structure-function relationship between the C-terminal segment of this toxin and its analgesic activity. To address this issue, we performed three MD simulations: one on the native structure and the other two on mutants of that structure. Results of these calculations suggest that the existence of glycine residues at the C-terminal segment stabilizes the protruding topology of the NC domain, which is considered an important determinant of the analgesic activity of BmK AGP-SYPU2.

Purification, characterization and functional expression of a new peptide with an analgesic effect from Chinese scorpion Buthus martensii Karsch (BmK AGP-SYPU1).

In this study, a new peptide named BmK AGP-SYPU1 with an analgesic effect was purified from the venom of Chinese scorpion Buthus martensi Karsch (BmK) through a four-step chromatographic process. The mouse twisting test was used to identify the target peptides in every separation step. The purified BmK AGP-SYPU1 was further qualified by RP-HPLC and HPCE. The molecular mass determined by the MALDI-4800-TOF/TOF MS for BmK AGP-SYPU1 was 7544 Da. Its primary structure of the N-terminal was obtained using Edman degradation. The gene sequence of BmK AGP-SYPU1 was cloned from the cDNA pool and genomic of scorpion glands, respectively, and then expressed in Escherichia coli. The sequence determination showed that BmK AGP-SYPU1 was composed of 66 amino acid residues with a new primary structure. The metal chelating affinity column and cation exchange chromatography were used to purify the recombinant BmK AGP-SYPU1. Consequently, the native and recombinant BmK AGP-SYPU1 showed similar analgesic effects on mice as assayed using a mouse twisting model. These results suggested that BmK AGP-SYPU1 is a new analgesic component found in the Chinese scorpion Buthus martensi Karsch.