Two novel diphoshinoamine ligands have been synthesized. Combination of Cr（Ⅲ） and methylaluminoxane（MAO） generated active catalytic system which can catalyze tetramerization of ethylene with high catalytic activi...Two novel diphoshinoamine ligands have been synthesized. Combination of Cr（Ⅲ） and methylaluminoxane（MAO） generated active catalytic system which can catalyze tetramerization of ethylene with high catalytic activity up to 2.5×10^6 g/mol Cr.h and high selectivity to produce 1-octene （Cs in products is being 89.80 wt%）.展开更多
Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction press...Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction pressure and Al/Cr molar ratio on ethylene tetramerization were investigated in detail. Chromium was uniformly and firmly immobilized on the support and could not be leached off by methylaluminoxane. The supported catalyst, upon being activated with methylaluminoxane, exhibited catalytic activity of 1.70×107 g/(mol Cr·h) for ethylene tetramerization to form 1-octene at a reaction temperatures of 80 ℃, a pressure of 2.0 MPa and an Al/Cr molar ratio of 300. The supported catalyst presented a good tolerance to high temperature.展开更多
The reductive cyclocoupling of isocyanides is a pivotal reaction that facilitates the rapid construction of intricate cyclic compounds in a single-step process.In this work,treatment of simple precursor1(Cp^(#)CrLCl,L...The reductive cyclocoupling of isocyanides is a pivotal reaction that facilitates the rapid construction of intricate cyclic compounds in a single-step process.In this work,treatment of simple precursor1(Cp^(#)CrLCl,L=CAAC,NHC,PCy_(3),or PPh_(2)Et;Cp^(#)=Cp^(*)or Cp^(*TMS))with XylNC(2,6-dimethylphenyl isocyanide)led to the reductive coupling of isocyanides,yielding either complex 2{(Cp^(*TMS)Cr)_(2)[μ-C_(4)(NXyl)_(4)]}or complex 6{(Cp^(*)CrCl)_(2)[μ-C_(4)(NXyl)_(4)]},corresponding to the tetramerization of isocyanides.Control experiments and in-situ monitoring were carried out to understand the reaction mechanism,revealing various side reaction pathways during the isocyanide tetramerization.SQUID and DFT calculations provided insights into the electronic structures.In complex 2,the energies of nonet and broken-symmetry singlet states are close and significantly lower than other spin states,indicating two independent highspin Cr(Ⅱ)centers with weak antiferromagnetic coupling.A similar situation is observed in complex 6,where two independent high-spin Cr(Ⅲ)centers are coupled antiferromagnetically.In both complexes 2 and 6,the tetrameric isocyanide rings,receiving two electrons from Cr centers,show averaged bond lengths and display moderate aromatic characteristics.展开更多
Objective:To study the effects of potassium channel tetramerization domain-containing 12 (KCTD-12) overexpression on in vitro proliferation and invasion of gastrointestinal stromal tumor cells.Methods:Gastrointestinal...Objective:To study the effects of potassium channel tetramerization domain-containing 12 (KCTD-12) overexpression on in vitro proliferation and invasion of gastrointestinal stromal tumor cells.Methods:Gastrointestinal stromal tumor cell lines were cultured and randomly divided into KCTD-12 overexpression group and NC overexpression group that were transfected with KCTD-12 overexpression plasmid and negative control plasmid respectively. 24 h after transfection, the expression of proliferation genes, apoptosis genes, PI3K and p38MAPK signaling pathway molecules as well as invasion genes in cells were detected. Results: Ki-67, SCIN, Bcl-2, p-PI3K, p-AKT, p-p38MAPK, CD146, PAR-2, SDF-1 and CXCR4 expression in KCTD-12 overexpression group were significantly lower than those in NC overexpression group while Bax, Caspase-3, Caspase-7, Caspase-9 and p-FOXO1 expression were significantly higher than those in NC overexpression group.Conclusion:KCTD-12 can inhibit the in vitro proliferation and invasion of gastrointestinal stromal tumor cells.展开更多
A new isopropenyl benzofuran-type tetramer was isolated from the roots of ligularia stenocephala and its structure was established by spectroscopic methods.
A hydrothermal reaction of copper acetate with ammonium molybdate, 4,4-bpy (4,4-bipyridine) and 1,10-phen (1,10-phenanthroline) led to the formation of brown crystals of [Cu2(1,10-phen)2(4,4-bpy)]2 [Mo8O26]4H2O 1. Si...A hydrothermal reaction of copper acetate with ammonium molybdate, 4,4-bpy (4,4-bipyridine) and 1,10-phen (1,10-phenanthroline) led to the formation of brown crystals of [Cu2(1,10-phen)2(4,4-bpy)]2 [Mo8O26]4H2O 1. Single-crystal X-ray analysis has revealed that 1 (C68H56N12O30Cu4Mo8) crystallizes in the triclinic system, space group P with a = 11.270(3), b = 13.113(6), c = 13.906(3) ? = 103.33(4), b = 98.54(2), g = 101.29(2)? V = 1920.1(1) ?3, Mr = 2542.93, Z = 1, Dc = 2.199 g/cm3, m = 2.435 mm-1, F(000) = 1240, the final R = 0.0445, wR = 0.1082 and S = 1.021 for 5052 observed reflections with I >2s(I). It consists of copper (Ⅰ) tetramer units and -[Mo8O26]4- anions, which are further attached into a three-dimensional framework through hydrogen bonding and - stacking interactions.展开更多
Combining with electrospray ionization(ESI)mass spectrometry,infrared photodissociation(IRPD)spectroscopy is a powerful method to study structures of cluster ions in the gas phase.In this paper,infrared photodissociat...Combining with electrospray ionization(ESI)mass spectrometry,infrared photodissociation(IRPD)spectroscopy is a powerful method to study structures of cluster ions in the gas phase.In this paper,infrared photodissociation spectrum of Pro_4H~+in the range of 2700–3600 cm 1was obtained experimentally.Both theoretically predicted spectra of the two most stable isomers of Pro4^(-1)and Pro4^(-2)obtained at the level of M062X/6-31+G(d,p)are in good consistent with the experimental results.The two isomers have similar structures and close energies.Both of them only consist of zwitterionic units,indicating the strong salt-bridged interactions inside the clusters.And the calculated collision cross section(ccs)of Pro4-1 is found to be very close to the experimental result previously reported.展开更多
N-acetylatedα-synuclein(αSyn)has long been established as an intrinsically disordered protein associated with a dysfunctional role in Parkinson’s disease.In recent years,a physiologically relevant,higher order conf...N-acetylatedα-synuclein(αSyn)has long been established as an intrinsically disordered protein associated with a dysfunctional role in Parkinson’s disease.In recent years,a physiologically relevant,higher order conformation has been identified as a helical tetramer that is tailored by buried hydrophobic interactions and is distinctively aggregation resistant.The canonical mechanism by which the tetramer assembles remains elusive.As novel biochemical approaches,computational methods,pioneering purification platforms,and powerful imaging techniques continue to develop,puzzling information that once sparked debate as to the veracity of the tetramer has now shed light upon this new counterpart inαSyn neurobiology.Nuclear magnetic resonance and computational studies on multimericαSyn structure have revealed that the protein folding propensity is controlled by small energy barriers that enable large scale reconfiguration.Alternatively,familial mutations ablate tetramerization and reconfigure polymorphic fibrillization.In this review,we will discuss the dynamic landscape ofαSyn quaternary structure with a focus on the tetrameric conformation.展开更多
Helicobacter pylori 3-Deoxy-D-manno-2-octulosonate-8-phosphate (KDO8P) synthase catalyzes the conversion of D-arabinose-5-phosphate (A5P) and phosphoenolpyruvate (PEP)
We investigate the quantum phase transition(QPT) and magnetocaloric effect(MCE) of a tetrameric chain with three-spin interaction using Green's function theory. The magnetization and gap analysis reveals a variety...We investigate the quantum phase transition(QPT) and magnetocaloric effect(MCE) of a tetrameric chain with three-spin interaction using Green's function theory. The magnetization and gap analysis reveals a variety of quantum phases tuned by magnetic field and three-spin interaction, which can open up an energy gap, giving rise to the occurrence of zero magnetization plateau. However, strong three-spin couplings causing strong frustration will destroy the intermediate 1/2 plateau with emergence of a new gapless phase between two cusps. It favors achieving an enhanced MCE at the critical fields, where the minima of isoentropes as well as the valley-peak structure of Gru¨neisen ratio, signaling the accumulation of entropy, lead to cooling via adiabatic(de)magnetization processes. It is also found that the temperature dependence of specific heat combined with Gru¨neisen ratio can testify various quantum phases explicitly.展开更多
Even for a 100 nm interparticle distance or a small change in particle shape,optical Fano-like plasmonic resonance mode usually vanishes completely.It would be remarkable if stable Fano-like resonance could somehow be...Even for a 100 nm interparticle distance or a small change in particle shape,optical Fano-like plasmonic resonance mode usually vanishes completely.It would be remarkable if stable Fano-like resonance could somehow be achieved in distinctly shaped nanoparticles for more than 1μm interparticle distance,which corresponds to the far electromagnetic field region.If such far-field Fano-like plasmonic resonance can be achieved,controlling the reversal of the far-field binding force can be attained,like the currently reported reversals for near-field cases.In this work,we have proposed an optical set-up to achieve such a robust and stable Fano-like plasmonic resonance,and comparatively studied its remarkable impact on controlling the reversal of near-and far-field optical binding forces.In our proposed set-up,the distinctly shaped plasmonic tetramers are half immersed(i.e.air-benzene)in an inhomogeneous dielectric interface and illuminated by?circular?polarized light.We have demonstrated significant differences between near-and far-field optical binding forces along with the Lorentz force field,which partially depends on the object’s shape.A clear connection is shown between the far-field binding force and the resonant modes,along with a generic mechanism to achieve controllable Fano-like plasmonic resonance and the reversal of the optical binding force in both far-and near-field configurations.展开更多
A new resveratrol tetramer, sinicin A was isolated from the roots of Ampelopsis sinica, with four known tetramers: vitisin A, cis-vitisin B, ampelopsin H and hopeaphenol. The structure and stereochemistry of sinicin A...A new resveratrol tetramer, sinicin A was isolated from the roots of Ampelopsis sinica, with four known tetramers: vitisin A, cis-vitisin B, ampelopsin H and hopeaphenol. The structure and stereochemistry of sinicin A have been established on the basis of 1D and 2D NMR spectroscopic techniques.展开更多
A new mixed-ligand Zn（II） complex, [Zn（4,4′-bipy）2（H2O）4]-2ANS·6H2O （1, 4,4′- bipy = 4,4′-bipyridine, HANS = 2-aminonaphthalene-l-sulfonic acid）, has been isolated and structurally characterized by sin...A new mixed-ligand Zn（II） complex, [Zn（4,4′-bipy）2（H2O）4]-2ANS·6H2O （1, 4,4′- bipy = 4,4′-bipyridine, HANS = 2-aminonaphthalene-l-sulfonic acid）, has been isolated and structurally characterized by single-crystal X-ray diffwaction, FT-IR spectrum, TG and elemental analysis. It crystallizes in the monoclinic system, space group P2 1/c with a = 12.4852（8）, b = 18.3163（12）, c = 10.9707（7） A, β = 114.2600（10）°, V= 2287.3（3） A3, Dc = 1.455 g/cm3, Mr = 1002.37, Z = 2, F（000） = 1048,μ = 0.704 mm＂1, the final R = 0.0408 and wR = 0.962 for 4029 observed reflections with I 〉 2σ（I）. Interestingly, an unusual one-dimensional （1D） water tape with cyclic tetrameric water clusters can be observed in 1, which are further trapped via Zn-O coordination bonds exhibiting a 2D Zn（Ⅱ）-water layer. These 2D Zn（Ⅱ）-water layers are stacked together into a 3D interdigitated supramolecular architecture via weak π…π interactions, in which free ANS anions are tightly filled by hydrogen-bonding interactions. Thus, π…π and classical hydrogen-bonding interactions are fotmd as main driving forces to stabilize the 2D Zn（Ⅱ）-water layers.展开更多
Analysis of the frequency of antigen-specific cytotoxic T lymphocytes (CTLs) ex vivo is largely dependent on the use of MHC/peptide tetramers. However, the latter reagents have not been widely available, most likely b...Analysis of the frequency of antigen-specific cytotoxic T lymphocytes (CTLs) ex vivo is largely dependent on the use of MHC/peptide tetramers. However, the latter reagents have not been widely available, most likely because of their costly and time-consuming production. In this report we utilized an economic strategy to construct HLA/peptide tetramers with recombinant peptide-linked β2 microglobulin (β2m). The HLA-A2-restricted, melanoma antigen MARTI-derived pep- tide MART127-35( AAGIGILTV) was fused to the N terminus of human β2m through a 15-amino acid (aa)-long linker before being refolded with the recombinant biotinylated HLA-A2 heavy chain ectodomain. The resulted 2-component (2C) monomer was then tetramerized with phycoerythin-labeled streptavidin. The experimental result showed that the 2C HLA-A2/ MART127-35 monomer was shown to bind to the HLA class complex-specific monoclonal antibody W6/32 and the HLA-A2/ MART127-35 complex-specific single chain antibody fragment (scFv) 8.3, suggesting the correctness of its specificity. Fur- thermore, the 2C HLA-A2/MART127-35 tetramer detected a specific CD8+ T cell population in HLA-A2-restricted melanoma infiltrating lymphocytes as the conventional 3C HLA-A2/MART127-35 tetramer. The yield of 2C HLA-A2/MART127-35 monomer was 2. 5 times more than that of the conventional 3C monomer. Taken together, these data indicate that the HLA-A2/ MART127-35 tetramer can be generated conveniently through the use of MART127-35 peptide-β2 m fusion proteins, which can fa- cilitate the monitoring of HLA-A2-restricted, MART1-specific CTL responses in patients with melanoma.展开更多
Nicotinamide adenine dinucleotide(NAD^(+))kinase(NADK)phosphorylates NAD^(+)to generate NADP^(+),which plays a crucial role in maintaining NAD^(+)/NADp^(+)homeostasis,cellular redox balance,and metabolism.However,how ...Nicotinamide adenine dinucleotide(NAD^(+))kinase(NADK)phosphorylates NAD^(+)to generate NADP^(+),which plays a crucial role in maintaining NAD^(+)/NADp^(+)homeostasis,cellular redox balance,and metabolism.However,how human NADK activity is regulated,and how dysregulation or mutation of NADK is linked to human diseases,such as cancers,are still not fully understood.Here,we present a cryo-EM structure of human tetrameric NADK and elaborate on the necessity of the NADK tetramer for its activity.The N-terminal region of human NADK,which does not exist in bacterial NADKs,modulates tetramer conformation,thereby regulating its activity.A methylation-deficient mutant,R45H,within the N-terminal region results in increased NADK activity and confers cancer chemotherapy resistance.Conversely,mutations in NADK identified among cancer patients alter the tetramer conformation,resulting in NADK inactivation and increasing the sensitivity of lung cancer cells to chemotherapy.Our findings partially unveil the structural basis for NADK regulation,offering insights into the cancer etiology of patients carrying NADK mutations.展开更多
In modern science and technology,on-demand control of the polarization and wavefront of electromagnetic(EM)waves is crucial for compact opto-electronic systems.Metasurfaces composed of subwavelength array structures i...In modern science and technology,on-demand control of the polarization and wavefront of electromagnetic(EM)waves is crucial for compact opto-electronic systems.Metasurfaces composed of subwavelength array structures inject infinite vitality to shape this fantastic concept,which has fundamentally changed the way humans engineer matter–wave interactions.However,achieving full-space arbitrarily polarized beams with independent wavefronts in broadband on a single metasurface aperture still remains challenging.Herein,the authors propose a generic method for broadband transmission-reflection-integrated wavefronts shaping with multichannel arbitrary polarization regulation from 8 to 16 GHz,which is based on the chirality effect of full-space non-interleaved tetrameric meta-molecules.Through superimposing eigen-polarization responses of the two kinds of enantiomers,the possibility for high-efficiency evolution of several typical polarization states with specific wavefronts is demonstrated.As proofs-of-concept,the feasibility of our methodology is validated via implementing miscellaneous functionalities,including circularly polarized(CP)beam splitting,linearly polarized(LP)vortex beams generation,and CP and LP multifoci.Meanwhile,numerous simulated and experimental results are in excellent agreement with the theoretical predictions.Encouragingly,this proposed approach imaginatively merges broadband polarization and phase control into one single full-space and shared-aperture EM device,which can extremely enhance the functional richness and information capacity in advanced integrated systems.展开更多
The current single-cell analysis technologies such as fluorescence-activated cell sorting(FACS)and fluorescence-activated droplet sorting(FADS)could decipher the cellular heterogeneity but were constrained by low sort...The current single-cell analysis technologies such as fluorescence-activated cell sorting(FACS)and fluorescence-activated droplet sorting(FADS)could decipher the cellular heterogeneity but were constrained by low sorting performance and cell viability.Here,an ultra-sensitive single-cell sorting platform has been developed by integrating the FADS technology with Tetramer-HCR-EvaGreen(THE)fluorescence signal amplification.The THE system produced much higher fluorescence signal than that of the single Tetramer or Tetramer-HCR signal amplification.Upon application to target MCF-7 cells,the platform exhibited high efficacy and selectivity while maintaining more than 95%cell viability.The THE-FADS achieved sorting efficiencies of 55.5%and 50.3%with purities of 91%and 85%for MCF-7 cells in PBS solutions and simulated serum samples,respectively.The sorted MCF-7 cells showed similar proliferation together with CK19 and EGFR mRNA expression compared with the control cells.The established THE-FADS showed the promising prospects to cellular heterogeneity understanding and personalized medicine.展开更多
文摘Two novel diphoshinoamine ligands have been synthesized. Combination of Cr（Ⅲ） and methylaluminoxane（MAO） generated active catalytic system which can catalyze tetramerization of ethylene with high catalytic activity up to 2.5×10^6 g/mol Cr.h and high selectivity to produce 1-octene （Cs in products is being 89.80 wt%）.
基金supported by the National Natural Science Foundation of China (U1162114)the PetroChina Innovation Foundation (2012D-5006-0501)+2 种基金the Tianjin Municipal Education Commission of China (20110505)the Natural Science Foundation of Tianjin (12JCQNJC06000)the Program for New Century Excellent Talents in University (NCET-07-0142)
文摘Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction pressure and Al/Cr molar ratio on ethylene tetramerization were investigated in detail. Chromium was uniformly and firmly immobilized on the support and could not be leached off by methylaluminoxane. The supported catalyst, upon being activated with methylaluminoxane, exhibited catalytic activity of 1.70×107 g/(mol Cr·h) for ethylene tetramerization to form 1-octene at a reaction temperatures of 80 ℃, a pressure of 2.0 MPa and an Al/Cr molar ratio of 300. The supported catalyst presented a good tolerance to high temperature.
基金the financial support by the National Natural Science Foundation of China(No.22201013)。
文摘The reductive cyclocoupling of isocyanides is a pivotal reaction that facilitates the rapid construction of intricate cyclic compounds in a single-step process.In this work,treatment of simple precursor1(Cp^(#)CrLCl,L=CAAC,NHC,PCy_(3),or PPh_(2)Et;Cp^(#)=Cp^(*)or Cp^(*TMS))with XylNC(2,6-dimethylphenyl isocyanide)led to the reductive coupling of isocyanides,yielding either complex 2{(Cp^(*TMS)Cr)_(2)[μ-C_(4)(NXyl)_(4)]}or complex 6{(Cp^(*)CrCl)_(2)[μ-C_(4)(NXyl)_(4)]},corresponding to the tetramerization of isocyanides.Control experiments and in-situ monitoring were carried out to understand the reaction mechanism,revealing various side reaction pathways during the isocyanide tetramerization.SQUID and DFT calculations provided insights into the electronic structures.In complex 2,the energies of nonet and broken-symmetry singlet states are close and significantly lower than other spin states,indicating two independent highspin Cr(Ⅱ)centers with weak antiferromagnetic coupling.A similar situation is observed in complex 6,where two independent high-spin Cr(Ⅲ)centers are coupled antiferromagnetically.In both complexes 2 and 6,the tetrameric isocyanide rings,receiving two electrons from Cr centers,show averaged bond lengths and display moderate aromatic characteristics.
文摘Objective:To study the effects of potassium channel tetramerization domain-containing 12 (KCTD-12) overexpression on in vitro proliferation and invasion of gastrointestinal stromal tumor cells.Methods:Gastrointestinal stromal tumor cell lines were cultured and randomly divided into KCTD-12 overexpression group and NC overexpression group that were transfected with KCTD-12 overexpression plasmid and negative control plasmid respectively. 24 h after transfection, the expression of proliferation genes, apoptosis genes, PI3K and p38MAPK signaling pathway molecules as well as invasion genes in cells were detected. Results: Ki-67, SCIN, Bcl-2, p-PI3K, p-AKT, p-p38MAPK, CD146, PAR-2, SDF-1 and CXCR4 expression in KCTD-12 overexpression group were significantly lower than those in NC overexpression group while Bax, Caspase-3, Caspase-7, Caspase-9 and p-FOXO1 expression were significantly higher than those in NC overexpression group.Conclusion:KCTD-12 can inhibit the in vitro proliferation and invasion of gastrointestinal stromal tumor cells.
基金supoaed by the National Natural Science Foundation of China(No.29972017)
文摘A new isopropenyl benzofuran-type tetramer was isolated from the roots of ligularia stenocephala and its structure was established by spectroscopic methods.
基金This work was supported by the National Natural Science Foundation of China (20073048) NSF of Fujian and the Chinese Academy of Sciences
文摘A hydrothermal reaction of copper acetate with ammonium molybdate, 4,4-bpy (4,4-bipyridine) and 1,10-phen (1,10-phenanthroline) led to the formation of brown crystals of [Cu2(1,10-phen)2(4,4-bpy)]2 [Mo8O26]4H2O 1. Single-crystal X-ray analysis has revealed that 1 (C68H56N12O30Cu4Mo8) crystallizes in the triclinic system, space group P with a = 11.270(3), b = 13.113(6), c = 13.906(3) ? = 103.33(4), b = 98.54(2), g = 101.29(2)? V = 1920.1(1) ?3, Mr = 2542.93, Z = 1, Dc = 2.199 g/cm3, m = 2.435 mm-1, F(000) = 1240, the final R = 0.0445, wR = 0.1082 and S = 1.021 for 5052 observed reflections with I >2s(I). It consists of copper (Ⅰ) tetramer units and -[Mo8O26]4- anions, which are further attached into a three-dimensional framework through hydrogen bonding and - stacking interactions.
基金Financial support from the National Natural Science Foundation of China(Nos.21172121,21475065)the Fundamental Research Funds for the Central Universities
文摘Combining with electrospray ionization(ESI)mass spectrometry,infrared photodissociation(IRPD)spectroscopy is a powerful method to study structures of cluster ions in the gas phase.In this paper,infrared photodissociation spectrum of Pro_4H~+in the range of 2700–3600 cm 1was obtained experimentally.Both theoretically predicted spectra of the two most stable isomers of Pro4^(-1)and Pro4^(-2)obtained at the level of M062X/6-31+G(d,p)are in good consistent with the experimental results.The two isomers have similar structures and close energies.Both of them only consist of zwitterionic units,indicating the strong salt-bridged interactions inside the clusters.And the calculated collision cross section(ccs)of Pro4-1 is found to be very close to the experimental result previously reported.
基金supported in part by Award No.18-7(to HRL)from the Commonwealth of Virginia’s Alzheimer’s and Related Diseases Research Award Fund,administered by the Virginia Center on Aging
文摘N-acetylatedα-synuclein(αSyn)has long been established as an intrinsically disordered protein associated with a dysfunctional role in Parkinson’s disease.In recent years,a physiologically relevant,higher order conformation has been identified as a helical tetramer that is tailored by buried hydrophobic interactions and is distinctively aggregation resistant.The canonical mechanism by which the tetramer assembles remains elusive.As novel biochemical approaches,computational methods,pioneering purification platforms,and powerful imaging techniques continue to develop,puzzling information that once sparked debate as to the veracity of the tetramer has now shed light upon this new counterpart inαSyn neurobiology.Nuclear magnetic resonance and computational studies on multimericαSyn structure have revealed that the protein folding propensity is controlled by small energy barriers that enable large scale reconfiguration.Alternatively,familial mutations ablate tetramerization and reconfigure polymorphic fibrillization.In this review,we will discuss the dynamic landscape ofαSyn quaternary structure with a focus on the tetrameric conformation.
文摘Helicobacter pylori 3-Deoxy-D-manno-2-octulosonate-8-phosphate (KDO8P) synthase catalyzes the conversion of D-arabinose-5-phosphate (A5P) and phosphoenolpyruvate (PEP)
基金Supported by the National Natural Science Foundation of China under Grant Nos.11204157,11174179,11247020the China Three Gorges University Project KJ2011B068
文摘We investigate the quantum phase transition(QPT) and magnetocaloric effect(MCE) of a tetrameric chain with three-spin interaction using Green's function theory. The magnetization and gap analysis reveals a variety of quantum phases tuned by magnetic field and three-spin interaction, which can open up an energy gap, giving rise to the occurrence of zero magnetization plateau. However, strong three-spin couplings causing strong frustration will destroy the intermediate 1/2 plateau with emergence of a new gapless phase between two cusps. It favors achieving an enhanced MCE at the critical fields, where the minima of isoentropes as well as the valley-peak structure of Gru¨neisen ratio, signaling the accumulation of entropy, lead to cooling via adiabatic(de)magnetization processes. It is also found that the temperature dependence of specific heat combined with Gru¨neisen ratio can testify various quantum phases explicitly.
基金the support of the internal grant of North South University 2018–19 and 2019–20(approved by the members of BOT,North South University,Bangladesh)along with the support of a TWAS international grant 2018–19(18-121 RG/PHYS/AS_I).
文摘Even for a 100 nm interparticle distance or a small change in particle shape,optical Fano-like plasmonic resonance mode usually vanishes completely.It would be remarkable if stable Fano-like resonance could somehow be achieved in distinctly shaped nanoparticles for more than 1μm interparticle distance,which corresponds to the far electromagnetic field region.If such far-field Fano-like plasmonic resonance can be achieved,controlling the reversal of the far-field binding force can be attained,like the currently reported reversals for near-field cases.In this work,we have proposed an optical set-up to achieve such a robust and stable Fano-like plasmonic resonance,and comparatively studied its remarkable impact on controlling the reversal of near-and far-field optical binding forces.In our proposed set-up,the distinctly shaped plasmonic tetramers are half immersed(i.e.air-benzene)in an inhomogeneous dielectric interface and illuminated by?circular?polarized light.We have demonstrated significant differences between near-and far-field optical binding forces along with the Lorentz force field,which partially depends on the object’s shape.A clear connection is shown between the far-field binding force and the resonant modes,along with a generic mechanism to achieve controllable Fano-like plasmonic resonance and the reversal of the optical binding force in both far-and near-field configurations.
基金This research program was supported by the National Natural Science Foundation of China (No. 30070+2 种基金889). The authors thank the Department of Instrumental Analysis Institute of Materia Medica Chinese Academy of Medical Sciences & Peking Union Col
文摘A new resveratrol tetramer, sinicin A was isolated from the roots of Ampelopsis sinica, with four known tetramers: vitisin A, cis-vitisin B, ampelopsin H and hopeaphenol. The structure and stereochemistry of sinicin A have been established on the basis of 1D and 2D NMR spectroscopic techniques.
基金Supported by the Advanced Project for Young Teachers in Tianjin Normal University
文摘A new mixed-ligand Zn（II） complex, [Zn（4,4′-bipy）2（H2O）4]-2ANS·6H2O （1, 4,4′- bipy = 4,4′-bipyridine, HANS = 2-aminonaphthalene-l-sulfonic acid）, has been isolated and structurally characterized by single-crystal X-ray diffwaction, FT-IR spectrum, TG and elemental analysis. It crystallizes in the monoclinic system, space group P2 1/c with a = 12.4852（8）, b = 18.3163（12）, c = 10.9707（7） A, β = 114.2600（10）°, V= 2287.3（3） A3, Dc = 1.455 g/cm3, Mr = 1002.37, Z = 2, F（000） = 1048,μ = 0.704 mm＂1, the final R = 0.0408 and wR = 0.962 for 4029 observed reflections with I 〉 2σ（I）. Interestingly, an unusual one-dimensional （1D） water tape with cyclic tetrameric water clusters can be observed in 1, which are further trapped via Zn-O coordination bonds exhibiting a 2D Zn（Ⅱ）-water layer. These 2D Zn（Ⅱ）-water layers are stacked together into a 3D interdigitated supramolecular architecture via weak π…π interactions, in which free ANS anions are tightly filled by hydrogen-bonding interactions. Thus, π…π and classical hydrogen-bonding interactions are fotmd as main driving forces to stabilize the 2D Zn（Ⅱ）-water layers.
文摘Analysis of the frequency of antigen-specific cytotoxic T lymphocytes (CTLs) ex vivo is largely dependent on the use of MHC/peptide tetramers. However, the latter reagents have not been widely available, most likely because of their costly and time-consuming production. In this report we utilized an economic strategy to construct HLA/peptide tetramers with recombinant peptide-linked β2 microglobulin (β2m). The HLA-A2-restricted, melanoma antigen MARTI-derived pep- tide MART127-35( AAGIGILTV) was fused to the N terminus of human β2m through a 15-amino acid (aa)-long linker before being refolded with the recombinant biotinylated HLA-A2 heavy chain ectodomain. The resulted 2-component (2C) monomer was then tetramerized with phycoerythin-labeled streptavidin. The experimental result showed that the 2C HLA-A2/ MART127-35 monomer was shown to bind to the HLA class complex-specific monoclonal antibody W6/32 and the HLA-A2/ MART127-35 complex-specific single chain antibody fragment (scFv) 8.3, suggesting the correctness of its specificity. Fur- thermore, the 2C HLA-A2/MART127-35 tetramer detected a specific CD8+ T cell population in HLA-A2-restricted melanoma infiltrating lymphocytes as the conventional 3C HLA-A2/MART127-35 tetramer. The yield of 2C HLA-A2/MART127-35 monomer was 2. 5 times more than that of the conventional 3C monomer. Taken together, these data indicate that the HLA-A2/ MART127-35 tetramer can be generated conveniently through the use of MART127-35 peptide-β2 m fusion proteins, which can fa- cilitate the monitoring of HLA-A2-restricted, MART1-specific CTL responses in patients with melanoma.
文摘Nicotinamide adenine dinucleotide(NAD^(+))kinase(NADK)phosphorylates NAD^(+)to generate NADP^(+),which plays a crucial role in maintaining NAD^(+)/NADp^(+)homeostasis,cellular redox balance,and metabolism.However,how human NADK activity is regulated,and how dysregulation or mutation of NADK is linked to human diseases,such as cancers,are still not fully understood.Here,we present a cryo-EM structure of human tetrameric NADK and elaborate on the necessity of the NADK tetramer for its activity.The N-terminal region of human NADK,which does not exist in bacterial NADKs,modulates tetramer conformation,thereby regulating its activity.A methylation-deficient mutant,R45H,within the N-terminal region results in increased NADK activity and confers cancer chemotherapy resistance.Conversely,mutations in NADK identified among cancer patients alter the tetramer conformation,resulting in NADK inactivation and increasing the sensitivity of lung cancer cells to chemotherapy.Our findings partially unveil the structural basis for NADK regulation,offering insights into the cancer etiology of patients carrying NADK mutations.
基金National Key Research and Development Program of China(SQ2022YFB3806200)National Natural Science Foundation of China(62301596,62101588)+1 种基金Young Talent Fund of Association for Science and Technology in Shaanxi(20240129)Postdoctoral Fellowship Program of CPSF(GZC20242285)。
文摘In modern science and technology,on-demand control of the polarization and wavefront of electromagnetic(EM)waves is crucial for compact opto-electronic systems.Metasurfaces composed of subwavelength array structures inject infinite vitality to shape this fantastic concept,which has fundamentally changed the way humans engineer matter–wave interactions.However,achieving full-space arbitrarily polarized beams with independent wavefronts in broadband on a single metasurface aperture still remains challenging.Herein,the authors propose a generic method for broadband transmission-reflection-integrated wavefronts shaping with multichannel arbitrary polarization regulation from 8 to 16 GHz,which is based on the chirality effect of full-space non-interleaved tetrameric meta-molecules.Through superimposing eigen-polarization responses of the two kinds of enantiomers,the possibility for high-efficiency evolution of several typical polarization states with specific wavefronts is demonstrated.As proofs-of-concept,the feasibility of our methodology is validated via implementing miscellaneous functionalities,including circularly polarized(CP)beam splitting,linearly polarized(LP)vortex beams generation,and CP and LP multifoci.Meanwhile,numerous simulated and experimental results are in excellent agreement with the theoretical predictions.Encouragingly,this proposed approach imaginatively merges broadband polarization and phase control into one single full-space and shared-aperture EM device,which can extremely enhance the functional richness and information capacity in advanced integrated systems.
基金funded by National Key Research and Development Program of China(grant number 2022YFC3502002)CAS-NSTDA Joint Research Project(2024)(grant number 101GJHZ2024017MI).
文摘The current single-cell analysis technologies such as fluorescence-activated cell sorting(FACS)and fluorescence-activated droplet sorting(FADS)could decipher the cellular heterogeneity but were constrained by low sorting performance and cell viability.Here,an ultra-sensitive single-cell sorting platform has been developed by integrating the FADS technology with Tetramer-HCR-EvaGreen(THE)fluorescence signal amplification.The THE system produced much higher fluorescence signal than that of the single Tetramer or Tetramer-HCR signal amplification.Upon application to target MCF-7 cells,the platform exhibited high efficacy and selectivity while maintaining more than 95%cell viability.The THE-FADS achieved sorting efficiencies of 55.5%and 50.3%with purities of 91%and 85%for MCF-7 cells in PBS solutions and simulated serum samples,respectively.The sorted MCF-7 cells showed similar proliferation together with CK19 and EGFR mRNA expression compared with the control cells.The established THE-FADS showed the promising prospects to cellular heterogeneity understanding and personalized medicine.
