Downregulation of the CD151 protects the cardiac function by the crosstalk between the endothelial cells and cardiomyocytes via exosomes.

BACKGROUND: Heart failure (HF) is the last stage in the progression of various cardiovascular diseases. Although it is documented that CD151 contributes to regulate the myocardial infarction, the function of CD151 on HF and involved mechanisms are still unclear. METHOD AND RESULTS: In the present study, we found that the recombinant adeno-associated virus (rAAV)-mediated endothelial cell-specific knockdown of CD151-transfected mice improved transverse aortic constriction (TAC)-induced cardiac function, attenuated myocardial hypertrophy and fibrosis, and increased coronary perfusion, whereas overexpression of the CD151 protein aggravated cardiac dysfunction and showed the opposite effects. In vitro, the cardiomyocytes hypertrophy induced by PE were significantly improved, while the proliferation and migration of cardiac fibroblasts (CFs) were significantly reduced, when co-cultured with the CD151-silenced endothelial cells (ECs). To further explore the mechanisms, the exosomes from the CD151-silenced ECs were taken by cardiomyocyte (CMs) and CFs, verified the intercellular communication. And the protective effects of CD151-silenced ECs were inhibited when exosome inhibitor (GW4869) was added. Additionally, a quantitative proteomics method was used to identify potential proteins in CD151-silenced EC exosomes. We found that the suppression of CD151 could regulate the PPAR signaling pathway via exosomes. CONCLUSION: Our observations suggest that the downregulation of CD151 is an important positive regulator of cardiac function of heart failure, which can regulate exosome-stored proteins to play a role in the cellular interaction on the CMs and CFs. Modulating the exosome levels of ECs by reducing CD151 expression may offer novel therapeutic strategies and targets for HF treatment.

Construction and Catalytic Study of Affinity Peptide Orientation and Light Crosslinking Immobilized Sucrose Isomerase.

A novel affinity peptide orientation and light-controlled covalent immobilized method was developed. Sucrose isomerase (SI) was selected as the model enzyme. Molecular simulation was first performed to select the targeted immobilization region. Subsequently, a short peptide (H2N-VNIGGX-COOH, VG) with high affinity to this region was rationally designed. Thereafter, 4-benzoyl-l-phenylalanine with the photosensitive group of benzophenone was introduced. Then, the affinity between the ligand and the SI was validated using molecular dynamics simulation. Thereafter, the SI was directionally immobilized onto the surface of the epoxy resin (EP) guided by VG via photo-crosslinking, and thus the oriented photo-crosslinking enzymes were obtained. The enzymatic activity, thermostability, and reusability of the affinity directional photo-crosslinked immobilized sucrose isomerase (hv-EP-VG-SI) were systematically studied. The oriented immobilization enzymes were significantly improved in recycling and heat resistance. Moreover, hv-EP-VG-SI retained more than 90% of the original activity and 50% of the activity after 11 cycles.

Expression profiles and potential functions of microRNAs in heart failure patients from the Uyghur population.

BACKGROUND AND PURPOSE: Existing studies have shown that circulating miRNA can be used as biomarkers of heart failure (HF). However, the circulating miRNA expression profile in Uyghur HF patients is unclear. In this study, we identified the miRNA profiles in the plasma of Uyghur HF patients and preliminarily explored their potential functions to provide new ideas for the diagnosis and treatment of HF. METHODS: Totally, 33 Uyghur patients with HF with reduced ejection fraction (<40%) were included in the HF group and 18 Uyghur patients without HF were included in the control group. First, high-throughput sequencing was used to identify differentially expressed miRNAs in the plasma of heart failure patients (n = 3) and controls (n = 3). Second, the differentially expressed miRNAs were annotated with online software and bioinformatics analysis was used to explore the critical roles of these circulating miRNAs in HF. Moreover, four selected differentially expressed miRNAs were validated by quantitative real-time PCR (qRT-PCR) in 15 controls and 30 HF patients. The diagnostic value of three successfully validated miRNAs for heart failure was assessed using receiver operating characteristic curve (ROC) analysis. Finally, to explore the expression levels of the three successfully validated miRNAs in HF hearts, thoracic aortic constriction (TAC) mice models were constructed and their expression in mice hearts was detected by qRT-PCR. RESULTS: Sixty-three differentially expressed miRNAs were identified by high-throughput sequencing. Of these 63 miRNAs, most were located on chromosome 14, and the OMIM database showed that 14 miRNAs were associated with HF. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that the target genes were mostly involved in ion or protein binding, the calcium signaling pathway, the mitogen-activated protein kinase (MAPK) signaling pathway, inositol phosphate metabolism, autophagy, and focal adhesion. Of the four selected miRNAs, hsa-miR-378d, hsa-miR-486-5p and hsa-miR-210-3p were successfully validated in the validation cohort and hsa-miR-210-3p had the highest diagnostic value for HF. Meanwhile, miR-210-3p was found to be significantly upregulated in the hearts of TAC mice. CONCLUSION: A reference set of potential miRNA biomarkers that may be involved in HF is constructed. Our study may provide new ideas for the diagnosis and treatment of HF.

The pattern of late gadolinium enhancement by cardiac MRI in fulminant myocarditis and its prognostic implication: a two-year follow-up study.

Background: Myocardial fibrosis, as quantified by late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR), provides valuable prognostic information for patients with myocarditis. However, due to the low incidence rate of fulminant myocarditis (FM) and accordingly small sample size, the knowledge about the role of LGE to patients with FM is limited. Methods and results: A total of 44 adults with viral-FM receiving the Chinese treating regimen were included in this retrospective study. They were divided into the low LGE group and the high LGE group according to the ratio of LGE to left ventricular mass (LGE mass%). CMR exams and LGE were performed after hemodynamic assistance at discharge in all patients with FM. Routine echocardiography parameters and global longitudinal strain (GLS) at discharge and at 2-year follow-up were obtained and then compared. Both left ventricular ejection fraction (LVEF) and GLS showed no significant difference in both groups at discharge, whereas significant differences were observed at 2-year follow-up between two groups. Moreover, there were significant improvements of LVEF and GLS in the low LGE group, but not in the high LGE group during the 2-year period. Furthermore, LGE mass% was negatively correlated with GLS and LVEF. Conclusions: There were two distinct forms of LGE presentation in patients with FM. Moreover, the cardiac function of patients with low LGE was significantly better than those with high LGE at 2-year follow-up. LGE mass% at discharge provided significant prognosis information about cardiac function of patients with FM.

Construction and characterization of a Myceliophthora thermophila lytic polysaccharide monooxygenase mutant S174C/A93C with improved thermostability.

Lytic polysaccharide monooxygenases (LPMOs) can oxidatively cleave the glycosidic bonds of crystalline polysaccharides, providing more accessible sites for polysaccharide hydrolases and promoting efficient conversion of biomass. In order to promote industrial applications of LPMOs, the stability of an LPMO of Myceliophthora thermophila C1 (MtC1LPMO) was improved by adding disulfide bonds in this study. Firstly, the structural changes of wild-type (WT) MtC1LPMO at different temperatures were explored using molecular dynamics simulations, and eight mutants were selected by combining the predicted results from Disulfide by Design (DBD), Multi agent stability prediction upon point mutations (Maestro) and Bridge disulfide (BridgeD) websites. Then, the enzymatic properties of the different mutants were determined after their expression and purification, and the mutant S174C/A93C with the highest thermal stability was obtained. The specific activities of unheated S174C/A93C and WT were 160.6 ± 1.7 U/g and 174.8 ± 7.5 U/g, respectively, while those of S174C/A93C and WT treated at 70 °C for 4 h were 77.7 ± 3.4 U/g and 46.1 ± 0.4 U/g, respectively. The transition midpoint temperature of S174C/A93C was 2.7 °C higher than that of WT. The conversion efficiency of S174C/A93C for both microcrystalline cellulose and corn straw was about 1.5 times higher than that of WT. Finally, molecular dynamics simulations revealed that the introduction of disulfide bonds increased the ß-sheet content of the H1-E34 region, thus improving the rigidity of the protein. Therefore, the overall structural stability of S174C/A93C was improved, which in turn improved its thermal stability.

Left ventricular function changes and echocardiographic predictors in adult survivors of fulminant myocarditis treated with the Chinese protocol.

Disagreement exists regarding the long-term prognosis and recovery of left ventricular (LV) function in patients with fulminant myocarditis (FM). This study reported the outcome and LV ejection fraction (EF) changes in FM treated with Chinese protocol, and assessed whether global longitudinal strain (GLS) by two-dimensional speckle tracking echocardiography (2-D STE) could provide additional information. This retrospective study included 46 FM adult patients who applied timely circulatory support and immunomodulatory therapy with adequate doses of both glucocorticoids and immunoglobulins as core approaches and survived after acute phase. They all presented with acute onset of cardiac symptoms < 2 weeks. LV end-diastolic dimensions, LVEF and GLS at discharge and 2-year were obtained and compared. We then performed linear regression and ROC analysis to determine independent factors to predict normalization of GLS at 2-year. At 2 years, the survival was 100% in our cohort. And the GLS improved modestly (15.40 ± 3.89% vs 17.24 ± 2.89%, P = 0.002). At two years, a proportion of patients whose LV function remained abnormal, being 22% evaluated by EF (< 55%) and higher to 37% by GLS (< 17%). Moreover, GLS at discharge but not at presentation correlated with GLS at 2-year (r = 0.402, P = 0.007). The FM adult treated with Chinese protocol have good survival and modest improvement of LV function during 2-year.

The effect of type 2 diabetes mellitus on multiple obstructive coronary artery disease.

BACKGROUND: Although type 2 diabetes mellitus (T2DM) individuals easily develop three-vessel disease (3VD) coronary artery disease (CAD), there is very little information available about their left ventricle (LV) functions. The purpose of this study is to evaluate the LV function using two-dimensional speckle tracking echocardiography (2-D STE) in T2DM patients with 3VD. METHODS: One hundred and three consecutive patients with confirmed 3VD CAD were enrolled and divided into two groups, while 53 patients with DM and 50 patients without. The control group was composed of 30 age- and sex-matched healthy individuals. All patients underwent 2-D STE and standard echocardiograms. The durations of DM and the level of HbA1c were also recorded. RESULT: Between the 3VD-DM and 3VD-non-DM groups, normal echocardiography did not reveal any appreciable differences. However, patients with 3VD-DM had significantly lower global longitudinal strain (GLS) than those with 3VD-non-DM (15.87 ± 2.51 vs.17.56 ± 2.72, p < .05) by 2-D STE strain measurement. Besides, patients whose duration of DM excess 5 years showed significant lower GLS than those with less than 5 years duration (14.25 ± 2.31 vs. 16.65 ± 1.96, p = .007). However, there was no difference in GLS between the 3VD-DM patients with HbA1c ≥ 7% and HbA1c < 7%. CONCLUSIONS: Compared to patients with 3VD alone, those with 3VD-DM have a lower cardiac function. In 3VD-DM patients, the duration of DM is a significant factor that contributes to cardiac function deterioration, whereas, the glucose control state has limited influence.

Bionics design of affinity peptide inhibitors for SARS-CoV-2 RBD to block SARS-CoV-2 RBD-ACE2 interactions.

Coronavirus Disease 2019 (COVID-19), has already posed serious threats and impacts on the health of the population and the country's economy. Therefore, it is of great theoretical significance and practical application value to better understand the process of COVID-19 infection and develop effective therapeutic drugs. It is known that the receptor-binding structural domain (SARS-CoV-2 RBD) on the spike protein of the novel coronavirus directly mediates its interaction with the host receptor angiotensin-converting enzyme 2 (ACE2), and thus blocking SARS-CoV-2 RBD-ACE2 interaction is capable of inhibiting SARS-CoV-2 infection. Firstly, the interaction mechanism between SARS-CoV-2RBD-ACE2 was explored using molecular dynamics simulation (MD) coupled with molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) free energy calculation method. The results of energy analysis showed that the key residues R403, R408, K417, and Y505 of SARS-CoV-2 RBD and the key residues D30, E37, D38, and Y41 of ACE2 were identified. Therefore, according to the hotspot residues of ACE2 and their distribution, a short peptide library of high-affinity SARS-CoV-2 RBD was constructed. And by using molecular docking virtual screening, six short peptides including DDFEDY, DEFEDY, DEYEDY, DFVEDY, DFHEDY, and DSFEDY with high affinity for SARS-CoV-2 RBD were identified. The results of MD simulation further confirmed that DDFEDY, DEYEDY, and DFVEDY are expected to be effective inhibitors. Finally, the allergenicity, toxicity and solubility properties of the three peptide inhibitors were validated.

Phloroglucinol, a clinical-used antispasmodic, inhibits amyloid aggregation and degrades the pre-formed amyloid proteins.

Amyloid proteins, such as ß-amyloid (Aß) and α-synuclein (α-syn), could form neurotoxic aggregates during the progression of neurodegenerative disorders. Phloroglucinol, a clinical-used drug for treating spasmodic pain, was predicted to cross the blood brain-barrier and possesses neuroprotective potential. In this study, we have found, for the first time, that phloroglucinol inhibited the formation of amyloid aggregates, and degraded pre-formed amyloid aggregates with the similar efficacy as curcumin, a widely known amyloid aggregation inhibitor. Moreover, phloroglucinol decreased the seeding during aggregation process and inhibited the aggregation of Aß1-42 with homocysteine (Hcy) seeds. Molecular docking analysis further demonstrated hydrophobic interactions and hydrogen bonds between phloroglucinol and Aß1-42/α-syn. Furthermore, phloroglucinol inhibited amyloid aggregates-induced cytotoxicity in neuronal cells and prevented Aß1-42 + Hcy aggregates-induced cognitive impairments in mice. All these results suggested that phloroglucinol possesses the ability to degrade pre-formed amyloid aggregates, to inhibit the seeding during amyloid aggregation, and to reduce the neurotoxicity, indicating the reposition possibility of phloroglucinol as a novel drug for treating neurodegenerative disorders.

The discovery and enzymatic characterization of a novel AA10 LPMO from Bacillus amyloliquefaciens with dual substrate specificity.

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes, which can catalyze the oxidative cleavage of polysaccharide ß-1,4 glycosidic bonds to improve the hydrolysis efficiency of the substrate by other glycoside hydrolases. To improve the conversion efficiency of cellulose and chitin, a strain was screened from the soil of Yuelu Mountain in Hunan province, China. The gene sequence of a novel AA10 LPMO (BaLPMO10) was successfully cloned from the genome of the strain and heterologously expressed in E. coli BL21 (DE3). The optimal enzyme activity of BaLPMO10 was observed at pH 6.0 and 70 °C using 2,6-dimethoxyphenol as substrate, and its maximum specific activity was 91.4 U/g. When BaLPMO10 synergized with glycoside hydrolase to degrade microcrystalline cellulose and colloidal chitin, the reducing sugar content increased by 7% and 23%, respectively, compared to glycoside hydrolase alone. Moreover, the results of molecular docking and molecular dynamics simulation showed that the distance between BaLPMO10 and cellohexaose were further than that of BaLPMO10 and chitohexaose, and the number of hydrogen bonds between BaLPMO10 and cellohexaose were lower than that of BaLPMO10 and chitohexaose. Finally, the hot spot residues of BaLPMO10 interacting with chitohexaose/cellohexaose were identified.

Diagnostic Accuracy of Global Longitudinal Strain for Detecting Exercise Intolerance in Patients with Ischemic Heart Disease.

Objective: Global longitudinal strain (GLS) is a sensitive and reproducible predictive factor in patients with ischemic heart disease (IHD), although its correlation with exercise tolerance is unknown. We aimed to identify the correlation between global longitudinal strain (GLS) and cardiopulmonary exercise testing (CPX) parameters and assess the prognostic implications and accuracy of GLS in predicting exercise intolerance in populations with ischemic heart disease (IHD) using CPET criteria. Methods: Prospectively, 108 patients with IHD underwent CPX and 2D speckle-tracking echocardiography. Correlation between GLS and multiple CPX variables was assessed using Spearman's correlation analysis and univariate regression analysis. A receiver operating characteristic (ROC) curve analysis was performed on GLS to detect exercise intolerance. Results: GLS was correlated with peak oxygen uptake (peak VO2; r = −0.438, p = 0.000), %PPeak VO2 (−0.369, p = 0.000), peak metabolic equivalents (METs@peak; r = −0.438, p < 0.01), and the minute ventilation−carbon dioxide production (VE/VCO2) slope (r = 0.257, p < 0.01). Weak-to-moderate correlations were also identified for the respiratory exchange rate at the anaerobic threshold (RER@AT), end-tidal carbon dioxide at the anaerobic threshold (PETCO2@AT), oxygen consumption at the anaerobic threshold (VO2@AT), carbon dioxide production at the anaerobic threshold (VCO2@AT), and metabolic equivalents at the anaerobic threshold (METs@AT; p < 0.01). On multivariate analysis, the results showed that age, the BMI, and GLS are independent predictors for reduced exercise capacity in patients with IHD (p < 0.01). The area under the ROC curve value of GLS for identifying patients with a peak VO2 of <14 mL/kg/min was 0.73 (p = 0.000). Conclusion: As a sensitive echocardiographic assessment of patients with ischemic heart disease, global longitudinal strain is an independent predictor of reduced exercise capacity and has a sensitivity of 74.2% and a specificity of 66.7% to detect exercise intolerance.

Design of carboxylated single-walled carbon nanotubes as highly efficient inhibitors against Aß40 fibrillation based on the HyBER mechanism.

Misfolding and the subsequent self-assembly of amyloid-ß protein (Aß) is very important in the occurrence of Alzheimer's disease (AD). Thus, inhibition of Aß aggregation is currently an effective method to alleviate and treat AD. Herein, a carboxylated single-walled carbon nanotube (SWCNT-COOH) was rationally designed based on the hydrophobic binding-electrostatic repulsion (HyBER) mechanism. The inhibitory effect of SWCNT-COOH on Aß fibrillogenesis was first studied. Based on the results of thioflavin T fluorescence and atomic force microscopy imaging assays, it was shown that SWCNT-COOH can not only effectively inhibit Aß aggregation, but also depolymerize the mature fibrils of Aß. In addition, its inhibitory action will be affected by the content of carboxyl groups. Moreover, the influence of SWCNT-COOH on cytotoxicity induced by Aß was investigated by the MTT method. It was found that SWCNT-COOH can produce an anti-Aß neuroprotective effect in vitro. Molecular dynamics simulations showed that SWCNT-COOH significantly destroyed the overall and internal structural stability of an Aß40 trimer. Moreover, SWCNT-COOH interacted strongly with the N-terminal region, turn region and C-terminal region of the Aß40 trimer via hydrogen bonds, salt bridges and π-π interactions, which triggered a large structural disturbance of the Aß40 trimer, reduced the ß-sheet content of the Aß40 trimer and led to more disorder in these regions. All the above data not only reveal the suppressive effect of SWCNT-COOH on Aß aggregation, but also reveal its inhibitory mechanism, which provides a useful clue to exploit anti-Aß drugs in the future.

Molecular Insights into the Inhibitory Effect of GV971 Components Derived from Marine Acidic Oligosaccharides against the Conformational Transition of Aß42 Monomers.

GV971 derived from marine acidic oligosaccharides has been used to cure Alzheimer's disease (AD). However, the molecular mechanism of its inhibition of the conformational transition of amyloid ß-proteins (Aß) is still unclear. Herein, molecular dynamics simulations were used to explore the molecular mechanism of the main GV971 components including DiM, TetraM, HexaM, and OctaM to inhibit the conformational conversion of the Aß42 monomer. It is found that the GV971 components inhibit the conformational transition from α-helix to ß-sheet and the hydrophobic collapse of the Aß42 monomer. In addition, the binding energy analysis implies that both electrostatic and van der Waals interactions are beneficial to the binding of GV971 components to the Aß42 monomer. Among them, electrostatic interactions occupy the dominant position. Moreover, the GV971 components mainly interact directly with the charged residues D1, R5, K16, and K28 by forming salt bridges and hydrogen bonds, which specifically bind to the N-terminal region of Aß42.

Removal of trace DNA toxic compounds using a Poly(deep eutectic solvent)@Biomass based on multi-physical interactions.

DNA toxic compounds (DNA-T-Cs), even in trace amounts, seriously threaten human health and must be completely eliminated. However, the currently used separation media face great challenges in removing trace DNA-T-Cs. Based on the functional advantages of deep eutectic solvents (DESs) and the natural features of biomass (BioM), a series of Poly(DES)@BioMs functioning as adsorbents were prepared for the removal of aromatic/hetero-atomic DNA-T-Cs at the ppm level. After optimisation of experimental conditions, the removal efficiency for DNA-T-Cs ranged from 92.4% to 96.0% with an initial concentration of 20.0 ppm, a temperature of 30 °C, duration of 30 min, and pH of 7.0. The removal processes between the DNA-T-Cs and Poly(DES)@BioMs are well described in the Temkin equilibrium and second-order kinetic adsorption models, and the desorption processes are well shown in the Korsmeryer-Peppas equilibrium and zero-order kinetic models. Molecular simulations revealed that the removal interactions include hydrogen bonding, π-π stacking, and hydrophobic/hydrophilic effects. The removal efficiency for the DNA-T-Cs at 8.0 ppm in industrial sewage ranged from 69.7% to 102%, while the removal efficiency for the DNA-T-Cs standing alone at 20.0 ppm in a methyl violet drug solution was 95.4%, confirming that the Poly(DES)@BioMs effectively removed trace DNA-T-Cs in field samples.

Improving the activity and stability of Bacillus clausii alkaline protease using directed evolution and molecular dynamics simulation.

Detergent enzymes have been developed extensively as eco-friendly substitutes for the harmful chemicals in detergent. Among them, alkaline protease accounts for a large share of detergent enzyme sales. Thus, improving the specific activity of alkaline protease could play an important role in reducing the cost of detergent enzymes. In our study, alkaline protease from Bacillus clausii (PRO) was used to construct a mutant library through directed evolution using error-prone PCR, and a variant (G95P) with 9-fold enhancement in specific activity was obtained. After incubation at a pH of 11.0 for 70 h, G95P maintained 67 % of its maximal activity, which was 46 % more than wild-type PRO (WT), indicating that G95P has better alkaline stability than WT. The thermostability of G95P was also enhanced, as G95P achieved 17 % initial activity after incubation for 50 h at 60 °C, while WT lost its activity. The MD simulation results verified that variant G95P possessed improved stability of its Gly95-Gly100 loop region and Arg19-Asp265 salt bridge, leading to enhanced stability and catalytic efficiency. This work enhances the understanding of the structure-function relationship of PRO and provides an academic foundation for improving the enzymatic properties of PRO to satisfy industrial requirements using protein engineering.

The food additive fast green FCF inhibits α-synuclein aggregation, disassembles mature fibrils and protects against amyloid-induced neurotoxicity.

α-Synuclein (α-syn) aggregates into cytotoxic amyloid fibrils, which are recognized as the defining neuropathological feature of Parkinson's disease (PD). Therefore, inhibiting α-syn fibrillogenesis and disrupting the preformed fibrils are both considered attractive strategies to cure PD. We discovered that a safe food additive, fast green FCF, is capable of inhibiting α-synuclein fibrillogenesis and reducing the related cytotoxicity. Thioflavin T fluorescence assays demonstrated that fast green FCF could inhibit the fibrillogenesis α-synuclein. In the presence of 100 µM fast green FCF, amorphous aggregates were formed and observed by atomic force microscopy. Toxicity assays in cell cultures revealed that fast green FCF significantly reduced the cytotoxicity of α-syn. Molecular dynamics simulations revealed the potential mechanism of the interactions between fast green FCF and α-synuclein. Fast green FCF greatly disrupted the α-synuclein pentamer and reduced the ß-sheet content by reducing both nonpolar and polar interactions. Furthermore, two binding sites were identified, named region I (Y39-K45) and region II (H50-Q62). Our data reveal that electrostatic interactions, hydrogen bonds, and π-π interactions synergistically contribute to the binding of fast green FCF to the α-synuclein pentamer. These results indicate that fast green FCF is a candidate prototype for the development of drugs against the aggregation of amyloid fibrils in PD.

Molecular basis for the inhibitory effects of 5-hydroxycyclopenicillone on the conformational transition of Aß40 monomer.

Previous studies have indicated that 5-hydroxycyclopenicillone (HCP), an active compound derived from marine sponge, could inhibit oligomerization of amyloid ß-protein (Aß). However, the molecular basis for the interaction between HCP and Aß remains unclear. Herein, all-atom molecular dynamics (MD) simulations were used to explore the conformational conversion of an Aß40 monomer at different concentrations (0-40 mM) of HCP at the atomic level. It is confirmed that the conformational transition of the Aß40 monomer is prevented by HCP in a concentration-dependent manner in silico. In 40 mM HCP solution, the initial α-helix-rich conformation of Aß40 monomer is kept under the action of HCP. The intra-peptide hydrophobic collapse and D23-K28 salt bridge are prevented by HCP. Moreover, it is indicated that the non-polar binding energy dominates the binding between HCP and Aß40 monomer as evaluated by molecular mechanics Poisson-Boltzmann surface area method. And, the residues of F4, Y10, V12, L17 and L34 in Aß40 might contribute to the binding energy in HCP-Aß40 complex. All these results elucidate the molecular mechanism underlying the inhibitory effects of HCP against the conformational transformation of Aß40, providing a support that HCP may be developed as a potential anti-Aß compound for the treatment of Aß-related diseases.Communicated by Ramaswamy H. Sarma.

Fast green FCF inhibits Aß fibrillogenesis, disintegrates mature fibrils, reduces the cytotoxicity, and attenuates Aß-induced cognitive impairment in mice.

Fast green FCF (FGF) is often used in foods, pharmaceuticals, and cosmetics. However, little is known about the interactions of FGF with amyloid-ß protein (Aß) associated with Alzheimer's disease. In this study, the inhibitory effects of FGF on Aß fibrillogenesis, the disruption of preformed Aß fibrils, the reduction of Aß-induced cytotoxicity, and the attenuation of Aß-induced learning and memory impairments in mice were investigated. FGF significantly inhibited Aß fibrillogenesis and disintegrated the mature fibrils as evidenced by thioflavin T fluorescence and atomic force microscopy studies. Co-incubation of Aß with FGF greatly reduced Aß-induced cytotoxicity in vitro. Moreover, FGF showed a protective effect against cognitive impairment in Aß-treated mice. Molecular dynamics simulations further showed that FGF could synergistically interact with the Aß17-42 pentamer via electrostatic interactions, hydrogen bonds and π-π interactions, which reduced the ß-sheet content, and disordered random coils and bend structures of the Aß17-42 pentamer. This study offers a comprehensive understanding of the inhibitory effects of FGF against Aß neurotoxicity, which is critical for the search of effective food additives that can combat amyloid-associated disease.

Enzymatic characterization, molecular dynamics simulation, and application of a novel Bacillus licheniformis laccase.

A new laccase gene from newly isolated Bacillus licheniformis TCCC 111219 was actively expressed in Escherichia coli. This recombinant laccase (rLAC) exhibited a high stability towards a wide pH range and high temperatures. 170% of the initial activity was detected at pH 10.0 after 10-d incubation, and 60% of the initial activity was even kept after 2-h incubation at 70 °C. It indicated that only single type of extreme environment, such as strong alkaline environment (300 K, pH 12) or high temperature (370 K, pH 7), did not show obvious impact on the structural stability of rLAC during molecular dynamics simulation process. But the four loop regions of rLAC where the active site is situated were seriously destroyed when strong alkaline and high temperature environment existed simultaneously (370 K, pH 12) because of the damage of hydrogen bonds and salt bridges. Moreover, this thermo- and alkaline-stable enzyme could efficiently decolorize the structurally differing azo, triphenylmethane, and anthraquinone dyes with appropriate mediator at pH 3.0, 7.0, and 9.0 at 60 °C. These rare characteristics suggested its high potential in industrial applications to decolorize textile dyeing effluent.