Search

Abstract Despite the broad potential applications of C-glycosides, facile synthetic methods remain scarce. Transforming glycosyltransferases with promiscuous or natural O-specific chemoselectivity to C-glycosyltransferases is challenging. Here, we employ rational directed evolution of the glycosyltransferase MiCGT to generate MiCGT-QDP and MiCGT-ATD mutants which either enhance C-glycosylation or switch to O-glycosylation, respectively. Structural analysis and computational simulations reveal that substrate binding mode govern C-/O-glycosylation selectivity. Notably, directed evolution and mechanism analysis pinpoint the crucial residues dictating the binding mode, enabling the rational design of four enzymes with superior non-inherent chemoselectivity, despite limited sequence homology. Moreover, our best mutants undergo testing with 34 substrates, demonstrating superb chemoselectivities, regioselectivities, and activities. Remarkably, three C-glycosides and an O-glycoside are produced on a gram scale, demonstrating practical utility. This work establishes a highly selective platform for diverse glycosides, and offers a practical strategy for creating various types of glycosylation platforms to access pharmaceutically and medicinally interesting products.

R-2-Bromobutyric acid is a very important intermediate for the synthesis of agrochemicals and pharmaceuticals. Bioresolution of rac-2-bromobutyric acid (rac-2-BBA) provides a promising process for R-2-bromobutyric acid (R-2-BBA) production. The fluoroacetate dehalogenase (FAcD) has been always studied in the defluorination process. We found that FAcD RPA1163 showed detectable activity but no enantioselectivity towards rac-2-BBA. The iterative saturation mutagenesis (ISM) of FAcD RPA1163 resulted in a mutant H155V/W156R/Y219M, which catalyzed the kinetic resolution of rac-2-BBA to produce R-2-BBA with enhanced activity and enantioselectivity (99.3% ee). The high preference for S-2-bromobutyric acid (S-2-BBA) is of synthetic value. Molecular docking analysis indicated that the H155V/W156R/Y219M mutation reduced steric hindrance and broadened the halide pocket. It is not only the steric hindrance but also the electrostatic environment that has an effect on the activity and enantioselectivity.

Glutamine, like glucose, is a major nutrient consumed by cancer cells, yet these cells undergo glutamine starvation in the cores of tumors, forcing them to evolve adaptive metabolic responses. Pharmacologically targeting glutamine metabolism or withdrawal has been exploited for therapeutic purposes, but does not always induce cancer cell death. The mechanism by which cancer cells adapt to resist glutamine starvation in cisplatin-resistant non-small-cell lung cancer (NSCLC) also remains uncertain. Here, we report the potential metabolic vulnerabilities of A549/DDP (drug-resistant human lung adenocarcinoma cell lines) cells, which were more easily killed by the iron chelator deferoxamine (DFO) during glutamine deprivation than their parental cisplatin-sensitive A549 cells. We demonstrate that phenotype resistance to cisplatin is accompanied by adaptive responses during glutamine deprivation partly via higher levels of autophagic activity and apoptosis resistance characteristics. Moreover, this adaptation could be explained by sustained glucose instead of glutamine-dominant complex II-dependent oxidative phosphorylation (OXPHOS). Further investigation revealed that cisplatin-resistant cells sustain OXPHOS partly via iron metabolism reprogramming during glutamine deprivation. This reprogramming might be responsible for mitochondrial iron-sulfur [Fe-S] cluster biogenesis, which has become an “Achilles’ heel,” rendering cancer cells vulnerable to DFO-induced autophagic cell death and apoptosis through c-Jun N-terminal kinase (JNK) signaling. Finally, in vivo studies using xenograft mouse models also confirmed the growth-slowing effect of DFO. In summary, we have elucidated the adaptive responses of cisplatin-resistant NSCLC cells, which balanced stability and plasticity to overcome metabolic reprogramming and permitted them to survive under stress induced by chemotherapy or glutamine starvation. In addition, for the first time, we show that suppressing the growth of cisplatin-resistant NSCLC cells via iron chelator-induced autophagic cell death and apoptosis was possible with DFO treatment. These findings provide a solid basis for targeting mitochondria iron metabolism in cisplatin-resistant NSCLC for therapeutic purposes, and it is plausible to consider that DFO facilitates in the improvement of treatment responses in cisplatin-resistant NSCLC patients.

Abstract Organofluorines are widely used in a variety of applications, ranging from pharmaceuticals to pesticides and advanced materials. The widespread use of organofluorines also leads to its accumulation in the environment, and two major questions arise: how to synthesize and how to degrade this type of compound effectively? In contrast to a considerable number of easy-access chemical methods, milder and more effective enzymatic methods remain to be developed. In this review, we present recent progress on enzyme-catalyzed C–F bond formation and cleavage, focused on describing C–F bond formation enabled by fluorinase and C–F bond cleavage catalyzed by oxidase, reductase, deaminase, and dehalogenase.

With the introduction of the global brain science program, the brain science and cognitive science are listed as one of the important research areas in China, the goal of which is to understand the function of the brain. In the human brain plan, the neurodegeneration and neurodevelopment in diseases and aging are one of the key areas of concern. However, lead is an environmental heavy metal neurotoxin, which can cause neurodegenerative diseases and affect brain health. At present, the mechanism of the lead-induced nervous system damage mainly focuses on the damage of lead to neurons, while the researches related to the repair of damaged nerve cells induced by the lead exposure have not been reported. The Transcriptome sequencing technology is direct detection of transcripts by the deep sequencing technology, which can more accurately measure the expression of transcripts, and is an inevitable link between genomic genetic information and the proteome of biological functions. In addition, the regulation of the transcription level is the most important regulation mode of organisms. Based on the characteristics of neurogenesis for nerve repair, the current study applied transcriptional sequencing technology to screen the differentially expressed genes in the choroid plexus of rats and to explore the changes in the expression of neurotrophic factors regulating neurogenesis in the choroid plexus of the lead-exposed rats. The results showed that the differentially expressed genes on choroid plexus of the lead exposed rats were related to neurogenesis. In the process of neurogenesis, the expression of nutritive and growth-promoting factors IGF1, EGFr, IGF1r, EGFr1, VEGFα , and TGFβ2 decreased, which suggested that these cytokines may be involved in the process of lead exposure neurogenesis, which needs further experimental verification. The findings of this study provide a new target for the mechanism research and prevention and control measures of brain nerve injury caused by the lead exposure.

The creation of C–C bonds is an effective strategy for constructing complex compounds from simple synthetic blocks. Although many methods have been developed for C–C bond construction, the stereoselective creation of new C–C bonds remains a challenge. The selectivities (enantioselectivity, regioselectivity, and chemoselectivity) of biocatalysts are higher than those of chemical catalysts, therefore biocatalysts are excellent candidates for use in stereoselective C–C bond formation. Here, we summarize progress made in the past 10 years in stereoselective C–C bond formation enabled by two classic types of enzyme, aldolases and hydroxynitrile lyases. The information in this review will enable the development of new routes to the stereoselective construction of C–C bonds.

Background/Aims: Avascular necrosis of the femoral head (ANFH) is the focus and difficulty of orthopedic diseases. Recently, tissue engineering bone for this disease has shown a good therapeutic effect. The aim of the present study was to investigate the therapeutic effect of basic fibroblast growth factor (FGF-2) as cytokines transfected bone marrow mesenchymal stem cells (BMSCs) in constructing tissue-engineered bone for avascular necrosis of the femoral head. Methods: The FGF-2 gene overexpressed lentivirus-transfected rBMSCs with xenogeneic antigen-extracted cancellous bone (XACB) to construct tissue engineered bone, and the model of early avascular necrosis of the femoral head was established by lipopolysaccharide (LPS) combined with hormone. The models were randomly divided into five groups: A (control), B (XACB), C (XACB+rBMSCs), D (XACB+rBMSCs+Lv-GFP), and E (XACB+rBMSCs+Lv-FGF-2/GFP) groups. The therapeutic effect of the tissue engineered bone for the avascular necrosis of the femoral head was evaluated by gross anatomy, X-ray examination, immunohistochemistry and H&E staining. Results: The FGF-2 gene was transfected into rBMSCs (Multiplicity of infection [MOI] = 100) by lentivirus, and its efficiency was above 95%. The rBMSCs were successfully transfected overexpressing FGF-2 by qPCR and western blot. After tissue engineering bone implantation, X-ray examination and gross specimen observation revealed that the repair area in the E group was > 80% at six weeks, the defect was completely repaired at 12 weeks, and osteogenesis was stronger, when compared with the other groups. For the X-ray score, vascular area density and new bone formation area were higher, when compared with the other groups, and the difference was statistically significant (P< 0.05). Conclusion: FGF-2 gene overexpression lentivirus transfection BMSCs combined with XACB to construct tissue engineered bone can effectively promote vascular regeneration, and improve the repair effect of avascular necrosis of the femoral head.

Widely distributed fluorocarboxylic acids have aroused worldwide environmental concerns due to its toxicity, persistence, and bioaccumulation. Enzyme-based eco-friendly biodegradation techniques have become increasingly important in treating fluorocarboxylic acids. Here we utilized in silico and in vitro approaches to investigate the defluorination mechanism of fluoroacetate dehalogenase (FAcD) toward monofluoropropionic acids at atomic-level. The experimentally determined kcat and kM for defluorination of 2-fluoropropionic acid are 330 ± 60 min−1 and 6.12 ± 0.13 mM. The in silico results demonstrated positive/negative correlations between activation barriers and structural parameters (e.g. distance and angle) under different enzymatic conformations. We also screened computationally and tested in vitro (enzyme assay and kinetic study) the catalytic proficiency of FAcD toward polyfluoropropionic acids and perfluoropropionic acids which are known to be challenging for enzymatic degradation. The results revealed potential degradation activity of FAcD enzyme toward 2,3,3,3-tetrafluoropropionic acids. Our work will initiate the development of a new “integrated approach” for enzyme engineering to degrade environmentally persistent fluorocarboxylic acids. Keywords: Quantum mechanics/molecular mechanics, Enzymatic Defluorination, Enzymatic conformations, Substitution effect

The robust designs of broadband extreme ultraviolet multilayers based on the multiobjective genetic algorithm are validated experimentally. In order to reduce the influence of random layer thickness fluctuations on the great deformation of the experimental reflection of extreme ultraviolet multilayer with a wide angular band, the multiobjective genetic algorithm has been improved to optimize the multilayer system composed by the layer thicknesses which can be controlled precisely. The robust designs of broadband Mo/Si multilayers were fabricated, and the experimental results were presented and analyzed, and then the advantage of robust multilayer designs was demonstrated.

The stressosome is a multiprotein complex that regulates the expression of stress response genes in Gram-positive bacteria. Here the authors characterize a stressosome from a Gram-negative bacterium, showing that one of the protein components senses oxygen through a bound haem.

Objective:This study aims to investigate the clinicopathologic significance of lymphatic vessel invasion (LVI) labeled by D2-40 monoclonal antibody in esophageal squamous cell carcinoma (ESCC).Methods:Immunohistochemical assay was used to detect the expression of D2-40 and LVI in 107 ESCC patients. Then, the correlation between the clinicopathologic feature and the overall survival time of the patients was analyzed.Results:The lymph node metastasis rates were 70% and 21% in the LVI-positive and LVI-negative groups, respectively. The nodal metastasis rate was higher in the LVI-positive group than in the LVI-negative group. Multivariate regression analysis showed that LVI was related to nodal metastasis (PP=0.014), multivariate regression analysis revealed that LVI was not an independent prognostic factor for overall survival in the ESCC patients (P=0.062). Lymphatic node metastasis (P=0.031), clinical stage (P=0.019), and residual tumor (P=0.026) were the independent prognostic factors.Conclusion:LVI labeled by D2-40 monoclonal antibody is a risk factor predictive of lymph node metastasis in ESCC patients.

The regioselectivity and the photochemical efficiency were investigated in the Paternò–Büchi reaction of 1,3-dimethylthymine (DMT) and 1,3-dimethyluracil (DMU) with benzophenone (1b) and some 4,4’-disubstituted derivatives (dimethoxy (1a), difluoro (1c), dichloro (1d), dibromo (1e) and dicyano benzophenone (1f)) that gives rise to two regioisomeric oxetanes, 2 and 3. The regioselectivity (the ratio of 2/3) decreased gradually for both DMT/DMU photochemical systems from 1a to 1f. That is, a halogen atom as an electron-withdrawing group (EWG) has a pronounced effect on the regioselectivity. However, the photochemical efficiency of the 1e systems did not show the expected increase, but decreased relative to systems with 1b. Temperature effects on the regioselectivity of 1b–e systems showed some interesting features for systems with heavy atoms (including the 1d and 1e systems), such as higher inversion temperatures, and an entropy-controlled regioselectively whereas the regioselectivity for two other systems (1b and 1c) is enthalpy–entropy controlled. A heavy atom effect is suggested to be responsible for these unusual phenomena based on the triplet-diradical mechanism of the Paternò–Büchi reaction.

Surveys were carried out in 2003–2006 to better understand the epidemiology of hantaviruses in the Inner Mongolia Autonomous Region of China (Inner Mongolia). Hemorrhagic fever with renal syndrome (HFRS) was first reported in this region in 1955 and has been an important public health problem here since then. During 1955–2006, 8,309 persons with HFRS were reported in Inner Mongolia (average incidence rate 0.89/100,000), and 261 (3.14%) died. Before the 1990s, all HFRS cases occurred in northeastern Inner Mongolia. Subsequently, HFRS cases were registered in central (1995) and western (1999) Inner Mongolia. In this study, hantaviral antigens were identified in striped field mice (Apodemus agrarius) from northeastern Inner Mongolia and in Norway rats (Rattus norvegicus) from middle and western Inner Mongolia. Phylogenetic analysis of hantaviral genome sequences suggests that HFRS has been caused mainly by Hantaan virus in northeastern Inner Mongolia and by Seoul virus in central and western Inner Mongolia.

One hundred and twenty patients with hypertensive thalamic hemorrhage were treated by different methods according to clinical situation and patients or family members. In this study 33 patients died: 7 patients were treated with conservative therapy, 6 patients with bilateral ventricle drainage, 8 patients with bilateral ventricle drainage plus hematoma puncture and aspiration, 12 patients with hematoma evacuation and decompressive cranioectomy. Comparison between different treatments revealed a statistically significant difference (P < 0.05). The treatment for hypertensive thalamic hemorrhage should be treated by different methods according to various clinical conditions to obtain better outcome. DOI：10.3969/j.issn.1672⁃6731.2012.04.020

Hantaviruses are among the most important zoonotic pathogens of humans and the subject of heightened global attention. Despite the importance of hantaviruses for public health, there is no consensus on their evolutionary history and especially the frequency of virus-host co-divergence versus cross-species virus transmission. Documenting the extent of hantavirus biodiversity, and particularly their range of mammalian hosts, is critical to resolving this issue. Here, we describe four novel hantaviruses (Huangpi virus, Lianghe virus, Longquan virus, and Yakeshi virus) sampled from bats and shrews in China, and which are distinct from other known hantaviruses. Huangpi virus was found in Pipistrellus abramus, Lianghe virus in Anourosorex squamipes, Longquan virus in Rhinolophus affinis, Rhinolophus sinicus, and Rhinolophus monoceros, and Yakeshi virus in Sorex isodon, respectively. A phylogenetic analysis of the available diversity of hantaviruses reveals the existence of four phylogroups that infect a range of mammalian hosts, as well as the occurrence of ancient reassortment events between the phylogroups. Notably, the phylogenetic histories of the viruses are not always congruent with those of their hosts, suggesting that cross-species transmission has played a major role during hantavirus evolution and at all taxonomic levels, although we also noted some evidence for virus-host co-divergence. Our phylogenetic analysis also suggests that hantaviruses might have first appeared in Chiroptera (bats) or Soricomorpha (moles and shrews), before emerging in rodent species. Overall, these data indicate that bats are likely to be important natural reservoir hosts of hantaviruses.

BackgroundTraditional Chinese medicinal herbs Cortex Moutan and Radix Salviae Milthiorrhizaeare are prescribed together for their putative cardioprotective effects in clinical practice. However, the rationale of the combined use remains unclear. The present study was designed to investigate the cardioprotective effects of paeonol and danshensu (representative active ingredient of Cortex Moutan and Radix Salviae Milthiorrhizae, respectively) on isoproterenol-induced myocardial infarction in rats and its underlying mechanisms.MethodologyPaeonol (80 mg kg(-1)) and danshensu (160 mg kg(-1)) were administered orally to Sprague Dawley rats in individual or in combination for 21 days. At the end of this period, rats were administered isoproterenol (85 mg kg(-1)) subcutaneously to induce myocardial injury. After induction, rats were anaesthetized with pentobarbital sodium (35 mg kg(-1)) to record electrocardiogram, then sacrificed and biochemical assays of the heart tissues were performed.Principal findingsInduction of rats with isoproterenol resulted in a marked (PConclusions/significanceThis study demonstrates the cardioprotective effect of paeonol and danshensu combination on isoproterenol-induced myocardial infarction in rats. The mechanism might be associated with the enhancement of antioxidant defense system through activating of Nrf2 signaling and anti-apoptosis through regulating Bax, Bcl-2 and Caspase-3. It could provide experimental evidence to support the rationality of combinatorial use of traditional Chinese medicine in clinical practice.

BackgroundInformation on polymorphic DNA in organelle genomes is essential for evolutionary and ecological studies. However, it is challenging to perform high-throughput investigations of chloroplast and mitochondrial DNA polymorphisms. In recent years, EcoTILLING stands out as one of the most universal, low-cost, and high-throughput reverse genetic methods, and the identification of natural genetic variants can provide much information about gene function, association mapping and linkage disequilibrium analysis and species evolution. Until now, no report exists on whether this method is applicable to organelle genomes and to what extent it can be used.Methodology/principal findingsTo address this problem, we adapted the CEL I-based heteroduplex cleavage strategy used in Targeting Induced Local Lesions in Genomes (TILLING) for the discovery of nucleotide polymorphisms in organelle genomes. To assess the applicability and accuracy of this technology, designated ORG-EcoTILLING, at different taxonomic levels, we sampled two sets of taxa representing accessions from the Brassicaceae with three chloroplast genes (accD, matK and rbcL) and one mitochondrial gene (atp6). The method successfully detected nine, six and one mutation sites in the accD, matK and rbcL genes, respectively, in 96 Brassica accessions. These mutations were confirmed by DNA sequencing, with 100% accuracy at both inter- and intraspecific levels. We also detected 44 putative mutations in accD in 91 accessions from 45 species and 29 genera of seven tribes. Compared with DNA sequencing results, the false negative rate was 36%. However, 17 SNPs detected in atp6 were completely identical to the sequencing results.Conclusions/significanceThese results suggest that ORG-EcoTILLING is a powerful and cost-effective alternative method for high-throughput genome-wide assessment of inter- and intraspecific chloroplast and mitochondrial DNA polymorphisms. It will play an important role in evolutionary and ecological biology studies, in identification of related genes associated with agronomic importance such as high yield and improved cytoplasmic quality, and for identifying mitochondrial point mutations responsible for diseases in humans and other animals.

Background: Buyang Huanwu decoction (BHD) is a traditional Chinese medicine herbal formula used for treating hypertension, particularly in the later stages of hypertension when it is associated with intracerebral hemorrhage. This study aims to investigate the treatment mechanism of BHD to provide a basis for its clinical application in hypertension treatment. Methods: Network pharmacology analysis and cell culture experiments were performed to explore the potential proteins and mechanisms of action of BHD against hypertension. Bioactive compounds related to BHD were screened, and relevant targets associated with hypertension and BHD were retrieved. Molecular docking technology was used to identify the effective signaling pathway based on the Kyoto Encyclopedia of Genes and Genomes and protein-protein interaction network cores. Lastly, the effects and mechanisms of BHD on salt-sensitive hypertensive endothelial cells were investigated. Results: Ninety-three potential therapeutic targets for BHD and salt-sensitive hypertension were found to be closely associated with the PI3K/Akt/eNOS signaling pathway and oxidative stress. Cell experiments further indicated the pivotal role of endothelial cells in hypertension, and validation analysis showed that BHD significantly preserved cell morphology, suppressed oxidative stress reactions, activated the PI3K/Akt/eNOS signaling pathways, preserved normal endothelial cell function, and reduced cell apoptosis. Conclusion: BHD effectively activates the PI3K/Akt/VEGF signaling pathway, attenuates oxidative stress-induced injury in endothelial cells exposed to high salt levels, and mitigates apoptosis, supporting the use of traditional Chinese medicine BHD in the treatment of salt-sensitive hypertension. [ABSTRACT FROM AUTHOR]

The crack initiation and life prediction of fiber-reinforced asphalt concrete (FRAC) surfacing for steel bridge decks under a cyclic vehicle load are analyzed from the perspective of damage mechanics. The damage field and the stress and strain field evolution rule of a composite beam in fatigue test are studied, and a fatigue failure criterion is proposed for steel deck FRAC surfacing. Bending fatigue tests are performed on composite beams composed of a steel deck and polyacrylonitrile (PAN)-fiber-reinforced Gussasphalt (GA), i.e., GA-PAN, concrete surfacing under different fiber content and temperature conditions. The damage evolution characteristics of GA-PAN concrete surfacing over the steel deck with different fiber lengths and volume ratios are predicted by analyzing the fatigue life equations. The results show that the steel bridge deck FRAC surfacing model can reflect the comprehensive influence of the fiber content and length on the fatigue performance of steel bridge AC. Specifically, a lower temperature results in the fiber more synergistically affecting the fatigue resistance of AC. Theoretically, the service performance of asphalt concrete increases with the increase of fiber length and content. The optimum fiber length and volume ratio of GA-PAN are found to be 9 mm and 0.46%−0.48%, respectively, considering the construction workability.