Monte-Carlo simulated annealing method (SA) was applied to the conformational analysis of flexible molecules such as peptides. The programs SAMM and SAPEP have been developed, using MM2 force field for organic molecul...Monte-Carlo simulated annealing method (SA) was applied to the conformational analysis of flexible molecules such as peptides. The programs SAMM and SAPEP have been developed, using MM2 force field for organic molecules and ECEPP/2 force field for peptides respectively.展开更多
The title compound,（E）-5-methoxy-2-（（4-methoxyphenylimino）methyl）phenol（C15H15NO3）,crystallizes in monoclinic,space group P21/c with a=9.4361（6）,b=10.6212（5）,c=12.9338（9）,β=93.064（5）o,V=1294.41（14）3...The title compound,（E）-5-methoxy-2-（（4-methoxyphenylimino）methyl）phenol（C15H15NO3）,crystallizes in monoclinic,space group P21/c with a=9.4361（6）,b=10.6212（5）,c=12.9338（9）,β=93.064（5）o,V=1294.41（14）3,Z=4,Dc=1.320 g/cm3,F（000）=544,Rint=0.116,T=296 K,μ=0.09 mm-1,the final R=0.051 and wR=0.148 for 1836 observed reflections with I2σ（I）.An extensive two-dimensional network of C–H…O hydrogen bonds and π-ring interactions are responsible for the crystal stabilization.Intermolecular hydrogen bonds and C–H…π interactions produce R22（14）,R44（30） and R44（31） rings.In addition to the molecular geometry from X-ray experiment,the molecular geometry of the title compound in the ground state has been calculated using the semi-empirical（AM1 and PM3） and density functional theory method（DFT）（B3LYP） with 6-31G（d） basis set.To determine the conformational flexibility,molecular energy profile of the title compound was obtained by semi-empirical（PM3 and AM1） and DFT/B3LYP calculations with respect to the selected degree of torsional freedom,which varied from –180° to ＋180° in a step of 10°.展开更多
A series of trans-4, 5-disubstituted -γ-butyrolactones are found to assume two different envelope conformations by means of nuclear magnetic resonance spectroscopy.
Through complexation reaction of arynyl Fe-S complexes A(μ-p-CH_3C_6H_4C≡CS)(μ- RS)Fe_2(CO)_6 with Co_2(CO)_6, eight mixed cluster complexes B[μ-p-CH_3C_6H_4C_2Co_2(CO)_6S](μ- RS)Fe_2(CO)_6 have been synthesized....Through complexation reaction of arynyl Fe-S complexes A(μ-p-CH_3C_6H_4C≡CS)(μ- RS)Fe_2(CO)_6 with Co_2(CO)_6, eight mixed cluster complexes B[μ-p-CH_3C_6H_4C_2Co_2(CO)_6S](μ- RS)Fe_2(CO)_6 have been synthesized. Reactivity of the complexation reaction is approximately equi- valent to that of the reaction of diarylacetylene with Co_2(CO)_8. Conformational analysis has shown that R groups in complexes A are linked to sulfur atoms by a-and e-bond, whereas that in B only by art e-type of bond.展开更多
Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement...Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement Spectroscopy(NOESY)and two-dimensional homonuclear J-correlated Spectroscopy(COSY).The result indicates that the overall structure of the single-stranded d(TTGGGGTT)is a right-handed B-type helix.展开更多
Conformations of Epristeride（ 17-β-N-t-butylcarboxamide-androst-3,5-diene-3-carboxylic acid） and its analogs were analyzed with the random search method and compared by means of the methods for steroid conformers, ...Conformations of Epristeride（ 17-β-N-t-butylcarboxamide-androst-3,5-diene-3-carboxylic acid） and its analogs were analyzed with the random search method and compared by means of the methods for steroid conformers, Connolly surfaces, dihedral angles, and molecular accessibility probes with protons, hydroxyl and methyl groups contained simultaneously. Analog d is different from others, which is in accordance with the preliminary clinical trial results under double blind conditions.展开更多
cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher c...cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher cis-selectivity of NaBH4 reduction of 2- monosubstituted cyclododecanones was rationalized by the mode of ＂corner position carbonyl participation＂. Crystal data for 2c： Mr = 263.21, monoclinic, space group P21/c, a = 1.11140（7）, b = 2.62590（17）, c = 0.91360（6） nm, β= 106.1840（10）°, V = 2.5606（3） nm^3, Dc = 1.366 g/cm^3, Z = 8, F（000） = 1104, μ（MoKα= 3.182 mm^-1, S = 0.837, the final R = 0.0460 and wR = 0.1033. Crystal X-ray diffraction analysis for 2c showed that its ring skeleton adopts [3333] conformation, in which the OH group presents at the side-exo position and the other one at the corner carbon. The 1H NMR data of 2 showed that 1-corner-R-2-side-exo-OH [3333] and 1-corner-OH-2-side-exo-R [3333] conformations coexist in dynamic equilibrium in the solution, but only the former presents in the crystal.展开更多
Conformation analysis of the model compounds for tunicamycin V and its natural donor substrate, UDP-N-acetylglucose, is performed to reveal the detail of the inhibition process.
Triadimefon(TDM)and cyproconazole(CPZ)are two triazoles widely used as fungicides.Several azoles were synthe-sised starting from commercial TDM and CPZ.The compounds were evaluated against phytopathogenic filamentous ...Triadimefon(TDM)and cyproconazole(CPZ)are two triazoles widely used as fungicides.Several azoles were synthe-sised starting from commercial TDM and CPZ.The compounds were evaluated against phytopathogenic filamentous fungi,including Aspergillus fumigatus(AF),A.niger(AN),A.ustus(AU),A.japonicus(AJ),A.terreus(AT),Fusarium oxyspo-rum and Botrytis cinerea isolated from grapevine in the province of San Juan,Argentina.Three of the synthesised compounds(1-(Biphenyl-4-yloxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one,1;2-(Biphenyl-4-yl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol,3;3-Cyclopropyl-2-(4’-fluorobiphenyl-4-yl)-1-(1H-1,2,4-triazol1-yl)butan-2-ol,4)presented remarkable in vitro fungicidal properties,with better effects than TDM and CPZ on some of the target fungi.Cytotoxicity was assessed using human lung fibroblasts MRC5.Derivative 1,with IC50 values of 389.4μM,was less toxic towards MRC-5 human lung fibroblasts than commercial TDM(248.5μM)and CPZ(267.4μM).Docking analysis and molecular dynamics simulations suggest that the compounds present the same interaction in the binding pocket of the CYP51B enzyme and with the same amino acids as CPZ.The derivatives investigated could be considered broad-spectrum but with some selectivity towards imperfect fungi.展开更多
The paper first analyzes the achievement of BOE＇s merging case and substantiates its success, then focuses on the strategy analysis of merger of the BOE, including the guidelines, merging way, strategic overall arran...The paper first analyzes the achievement of BOE＇s merging case and substantiates its success, then focuses on the strategy analysis of merger of the BOE, including the guidelines, merging way, strategic overall arrangement, culture conformity, financial guarantee etc., in a bid to offer valuable experience and reference function for the Chinese enterprises.展开更多
The crystal structure of the title compound ((C 6H 5CONC 6H 4S) 2, M r =229) has been determined by X ray diffraction analysis. The crystal belongs to triclinic space group P 1 with cell parameters: a=...The crystal structure of the title compound ((C 6H 5CONC 6H 4S) 2, M r =229) has been determined by X ray diffraction analysis. The crystal belongs to triclinic space group P 1 with cell parameters: a=7.957(4), b=11.570(7), c=12 335(6), α=76.68(4), β=81.48(4), γ=87.26(4)°, V=1092.9 3, Z=2, D c =1 39g/cm 3, F(000)=476, μ (Mo Kα )=2.7mm -1 . The final R factor is 0.0373 for 3764 observed reflections. The result of X ray diffraction analysis indicates that all of these single bond lengths are obviously shorter than that of standard single bond. Those atoms might take part in a conjugate system. The electrons for sp 3 hybridized S(1) and S(2) move toward two sides and the densities of electronic cloud among them are reduced and can be easily broken. The obtained results can explain the reaction mechanism of the title compound.展开更多
A new coordination compound Zn（2,4＇-bpt）2（H2O）（1） based on the versatile ligand 2,4＇-Hbpt（2,4？-Hbpt = 3-（2-pyridyl）-5-（4-pyridyl）-1H-1,2,4-triazole） was prepared by hydrothermal reactions. The structure...A new coordination compound Zn（2,4＇-bpt）2（H2O）（1） based on the versatile ligand 2,4＇-Hbpt（2,4？-Hbpt = 3-（2-pyridyl）-5-（4-pyridyl）-1H-1,2,4-triazole） was prepared by hydrothermal reactions. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, X-ray powder diffraction, IR spectrum analysis and thermogravimetric analysis. Single-crystal X-ray diffraction analysis indicates that the complex belongs to monoclinic system, space group C2/c with a = 23.877（3）, b = 0.7483（9）, c = 1.2492（2） A, b = 92.681（2）°, V = 2230.6（4） A^3, Z = 4, Dc = 1.572 g/cm^3, m = 1.143 mm^-1, Mr = 527.85 and F（000） = 1080. The final R = 0.0581 and wR = 0.0898 with I 〉 2s（I）. 1 is a 0D motif which is connected by hydrogen bonds to form a corrugated 1D pattern. In addition, 1 shows strong photoluminescent emissions in the solid state at room temperature which can be used as potential optical materials. Theoretical calculations based on density functional theory（DFT） were employed in order to explicate the stability and chemical reactivity of 2,4＇-Hbpt with different conformations. The results indicated that conformation I is more stable and prior to coordination in the reactions.展开更多
Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which...Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which is independent of fluorophore concentrations, scattering and bleaching, is a suitable tool to analyze membrane proteins in a single cell. Ferroportin（FPN）, a multi-ion exporter in vertebrates, was modulated by metal ions with unknown mechanism. Herein, we fused green fluorescence protein on Cterminal of FPN（FPN-eGFP） and applied fluorescence lifetime to monitor conformation changes of FPN in a live cell. The fluorescence lifetime distribution showed a shift to shorter lifetime upon Mn^（2＋） treatment,suggesting a preference conformation of FPN in Mn^（2＋） exposure. It is also observed that the lifetime（rather than intensity） measurement was not strongly influenced by laser power. The observed fluorescence lifetime changes of FPN-eGFP upon Mn^（2＋） treatments indicated that extracellular metal ions can modulate FPN through conformation exchanges between several different states.展开更多
The need for the analysis of modern businesses is rapidly increasing as the supporting enterprise systems generate more and more data.This data can be extremely valuable for executing organizations because the data al...The need for the analysis of modern businesses is rapidly increasing as the supporting enterprise systems generate more and more data.This data can be extremely valuable for executing organizations because the data allows constant monitoring,analyzing,and improving the underlying processes,which leads to the reduction of cost and the improvement of the quality.Process mining is a useful technique for analyzing enterprise systems by using an event log that contains behaviours.This research focuses on the process discovery and refinement using real-life event log data collected from a large multinational organization that deals with coatings and paints.By investigating and analyzing their order handling pro-cesses,this study aims at learning a model that gives insight inspection of the processes and performance analysis.Furthermore,the animation is also performed for the better inspection,diagnostics,and compliance-related questions to specify the system.The configuration of the system and the conformance checking for further enhancement is also addressed in this research.To achieve the objectives,this research uses process mining techniques,i.e.process discovery in the form of formal Petri nets models with the help of process maps,and process refinement through conformance checking and enhancement.Initially,the identified executed process is reconstructed by using the process discovery techniques.Following the reconstruction,we perform a deep analysis for the underlying process to ensure the process improvement and redesigning.Finally,some recommendations are made to improve the enterprise management system processes.展开更多
The crystal structure of the title compound cis 2 (P, P Diethoxy)phosphono( m nitro)benzyloxy 4 Phenyl 5,5 Dimethyl 1,3,2 Dioxaphosphorinane 2 Sulfide, C 22 H 29 NO 8P 2S, was determin...The crystal structure of the title compound cis 2 (P, P Diethoxy)phosphono( m nitro)benzyloxy 4 Phenyl 5,5 Dimethyl 1,3,2 Dioxaphosphorinane 2 Sulfide, C 22 H 29 NO 8P 2S, was determined by single crystal X ray diffraction. It crystallizes in the monoclinic system, space group P2 1/c, with M r=529.49, a=9.888(2), b=20.831(4), c=12.797(3) , β=94.42(3)°, V=2628(1) 3, Z=4, D x =1.338 g/cm 3 , λ=0.71073 , μ =0.2796 mm 1 and F(000) =556. The structure was solved by direct methods. The final R factor is 0.052 and R w is 0.057 for 1793 unique observed reflections I≥3σ(I) . A cis configuration and a preferred chair conformation for the molecule have been established by X ray diffraction analysis. The results presented also give a good explanation to the correlation between the configurational assignments and the regularity in the chemical shifts of C 4-H and 31 P NMR.展开更多
Chemical investigation of Beouverio felina,a marine-derived entomopathogenic fungus,obtained two new destruxin hexadepsipeptides(1 and 2)containing an/.-Ala^(5)residue instead of the usual A/-Me-L-Ala^(5).Interestingl...Chemical investigation of Beouverio felina,a marine-derived entomopathogenic fungus,obtained two new destruxin hexadepsipeptides(1 and 2)containing an/.-Ala^(5)residue instead of the usual A/-Me-L-Ala^(5).Interestingly,the presence of the/.-Ala^(5)residue enabled two slowly-exchanging solution conformers with cis/trons(ILE^(3))-(A/-Me-Val^(4))amide bond for 1 and 2 with 1.5:1 and 1:1 cis/trans ratios,respectively,while only the conformer with c/s amide bond was found in the solid-state.The solution and solid-state conformers were studied by NMR,X-ray diffraction and solution and solid-state ECD measurements,as well as by TDDFT-ECD calculations.Structural(conformational)parameter-activity correlations suggested that the extended destruxin geometry with the preferred c/s(ILE^(3))-(A/-Me-Val^(4))bond probably resulted in improved bioactivity and reduced toxicity for the destruxin class.This was the first report on the interconversion phenomenon of cis/trans amide bonds of destruxin class,which could give insights in the development of bioactive destruxin agents with lower toxicity.展开更多
For nanochemistry, precise manipulation of nanoscalestructures and the accompanying chemical properties atatomic precision is one of the greatest challenges today. Thescientific community strives to develop and design...For nanochemistry, precise manipulation of nanoscalestructures and the accompanying chemical properties atatomic precision is one of the greatest challenges today. Thescientific community strives to develop and design customizednanomaterials, while molecular interactions often serve as key toolsor probes for this atomically precise undertaking. In thisPerspective, metal nanoclusters, especially gold nanoclusters,serve as a good platform for understanding such nanoscaleinteractions. These nanoclusters often have a core size of about 2nm, a defined number of core metal atoms, and protecting ligandswith known crystal structure. The atomically precise structure ofmetal nanoclusters allows us to discuss how the molecularinteractions facilitate the systematic modification and functionalization of nanoclusters from their inner core, through the ligandshell, to the external assembly. Interestingly, the atomic packing structure of the nanocluster core can be affected by forces on thesurface. After discussing the core structure, we examine various atomic-level strategies to enhance their photoluminescent quantumyield and improve nanoclusters’ catalytic performance. Beyond the single cluster level, various attractive or repulsive molecularinteractions have been employed to engineer the self-assembly behavior and thus packing morphology of metal nanoclusters. Themethodological and fundamental insights systemized in this review should be useful for customizing the cluster structure andassembly patterns at the atomic level.展开更多
A DFT calculations are carried out at UB3LYP/6-311＋ ＋G （3df, 2p） levels of theory to study electrocyclic thermal cleavage of four （R） derivatives of unsaturated bicyclic diaziridines, Ix-R, to produce correspond...A DFT calculations are carried out at UB3LYP/6-311＋ ＋G （3df, 2p） levels of theory to study electrocyclic thermal cleavage of four （R） derivatives of unsaturated bicyclic diaziridines, Ix-R, to produce corresponding （Z） and （E） azomethine imides （2X-Z, 2X-E, 3X-Z and 3X-E）, where X=H, Me, t-Bu and Ph. Cleavage of 1X-R series to form the most stable 3X-Z product, （path 2） is found the favored procedure because of delocalized negative charge on five atoms and lower steric effect in related transition state. According to IRC calculations in paths 1 and 2, C6--N1 bond is cleaved before the rate determinating step （transition state）. The stability of unsaturated bicyclic diaziridines and their corresponding （Z） and （E） azomethine imides is in the following order in gas phase and chloroform, tetrahydrofuran, and acetone solvents： 3X-Z〈3X-F〈2X-Z 〈2X-E 〈 1X-R 〈 1X-S.展开更多
5, 10, 15-Triphenyl-20-{2-[alpha-(adenine-9) acetylamino]} phenyl porphyrin (1), 5,10,15-triphenyl-20-{2-[alpha-(cytosine-]}acetylamino]} phenyl porphyrin (2), 5, 10, 15-triphenyl-20-{4-[alpha(cytosine-1)ethoxy]} I I ...5, 10, 15-Triphenyl-20-{2-[alpha-(adenine-9) acetylamino]} phenyl porphyrin (1), 5,10,15-triphenyl-20-{2-[alpha-(cytosine-]}acetylamino]} phenyl porphyrin (2), 5, 10, 15-triphenyl-20-{4-[alpha(cytosine-1)ethoxy]} I I phenyl porphyrin (3) and their zinc complexes Zn-1, Zn-2 and Zn-3 have been prepared and characterized by H-1 NMR spectra, elemental analyses, electronic absorption spectra and mass spectra (FAB). Intramolecular pi-pi interactions and intramolecular metal-pi interaction for 1, 2, Zn-1, and Zn-2 have been investigated by several methods. H-1 NMR studies demonstrate that the porphyrin pi-system in 1 and 2 is parallel to the adenine and the cytosine aromatic ring, respectively. The electronic absorption spectral properties of free porphyrin derivatives and their zinc complexes have been compared with those of H2TPP and ZnTPP. The results show that the UV-vis spectra of 1 and 2 are the same as that of H2TPP, whereas the spectra of their zinc complexes show 7 nm red shifts of the Soret bands compared to that of ZnTPP. The emission spectra of Zn-1 and Zn-2 are independent of excitation wavelength. From combination of the evidence of absorption and emission spectra it is suggested the existence of intramolecular metal-pi interaction in Zn-1 and Zn-2. The results of conformational analysis agreed quite nicely with that of experiments, thus it was further to validate the experimental conclusions.展开更多
Biocatalysts are intrinsically reactive and hence their operational stability is of vital significance for any bioprocess. The setback in biocatalyst stability has been tackled from diverse prospects. Inherently, stab...Biocatalysts are intrinsically reactive and hence their operational stability is of vital significance for any bioprocess. The setback in biocatalyst stability has been tackled from diverse prospects. Inherently, stable biocatalysts are markedly realized and a regular attempt is being made to seek out new organisms that harbor them. Here, we analyzed the industrial biocatalyst lipase A （Native） of Bacillus subtilis and its six thermostable mutants （2M, 3M, 4M, 6M, 9M and 12M） computationally using conformational sampling technique. Consequently, the various structural events deciphering thermostability like root mean square deviation, root mean square fluctuation, radius of gyration and polar surface area showed mutant 12M to be highly stable with statistical validation. Besides, static model analysis involving intra-molecular interactions, secondary structure, solvent accessibility, hydrogen bond pattern, simulated thermal denaturation and desolvation energy also supported 12M comparatively. Of note, the presence of high secondary structural rigidity and hydrogen bonds increased thermostability and functionality of 12M, thus selecting it as a best template for designing thermostable lipases in future. Also, this study has a significant implication toward a better understanding of conformational sampling in enzyme catalysis and enzyme engineering.展开更多
文摘Monte-Carlo simulated annealing method (SA) was applied to the conformational analysis of flexible molecules such as peptides. The programs SAMM and SAPEP have been developed, using MM2 force field for organic molecules and ECEPP/2 force field for peptides respectively.
基金The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayis University, Turkey, for the use of the Stoe IPDSII diffractometer (purchased under grant No F279 of the University Research Fund)
文摘The title compound,（E）-5-methoxy-2-（（4-methoxyphenylimino）methyl）phenol（C15H15NO3）,crystallizes in monoclinic,space group P21/c with a=9.4361（6）,b=10.6212（5）,c=12.9338（9）,β=93.064（5）o,V=1294.41（14）3,Z=4,Dc=1.320 g/cm3,F（000）=544,Rint=0.116,T=296 K,μ=0.09 mm-1,the final R=0.051 and wR=0.148 for 1836 observed reflections with I2σ（I）.An extensive two-dimensional network of C–H…O hydrogen bonds and π-ring interactions are responsible for the crystal stabilization.Intermolecular hydrogen bonds and C–H…π interactions produce R22（14）,R44（30） and R44（31） rings.In addition to the molecular geometry from X-ray experiment,the molecular geometry of the title compound in the ground state has been calculated using the semi-empirical（AM1 and PM3） and density functional theory method（DFT）（B3LYP） with 6-31G（d） basis set.To determine the conformational flexibility,molecular energy profile of the title compound was obtained by semi-empirical（PM3 and AM1） and DFT/B3LYP calculations with respect to the selected degree of torsional freedom,which varied from –180° to ＋180° in a step of 10°.
文摘A series of trans-4, 5-disubstituted -γ-butyrolactones are found to assume two different envelope conformations by means of nuclear magnetic resonance spectroscopy.
文摘Through complexation reaction of arynyl Fe-S complexes A(μ-p-CH_3C_6H_4C≡CS)(μ- RS)Fe_2(CO)_6 with Co_2(CO)_6, eight mixed cluster complexes B[μ-p-CH_3C_6H_4C_2Co_2(CO)_6S](μ- RS)Fe_2(CO)_6 have been synthesized. Reactivity of the complexation reaction is approximately equi- valent to that of the reaction of diarylacetylene with Co_2(CO)_8. Conformational analysis has shown that R groups in complexes A are linked to sulfur atoms by a-and e-bond, whereas that in B only by art e-type of bond.
文摘Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement Spectroscopy(NOESY)and two-dimensional homonuclear J-correlated Spectroscopy(COSY).The result indicates that the overall structure of the single-stranded d(TTGGGGTT)is a right-handed B-type helix.
基金Supported by the National Natural Science Foundation of China(No. 30170808) and the Natural Science Foundation of Guang-dong Province(No. 010418).
文摘Conformations of Epristeride（ 17-β-N-t-butylcarboxamide-androst-3,5-diene-3-carboxylic acid） and its analogs were analyzed with the random search method and compared by means of the methods for steroid conformers, Connolly surfaces, dihedral angles, and molecular accessibility probes with protons, hydroxyl and methyl groups contained simultaneously. Analog d is different from others, which is in accordance with the preliminary clinical trial results under double blind conditions.
基金Presented in part at the Third National Symposium of the Chinese Chemical Society on Organic Chemistry, Lanzhou, China, August, 2004 (for abstract, see Chin. J. Org. Chem., 2004, Suppl. 365)This project was supported by the National Natural Science Foundation of China (No. 20072053)
文摘cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher cis-selectivity of NaBH4 reduction of 2- monosubstituted cyclododecanones was rationalized by the mode of ＂corner position carbonyl participation＂. Crystal data for 2c： Mr = 263.21, monoclinic, space group P21/c, a = 1.11140（7）, b = 2.62590（17）, c = 0.91360（6） nm, β= 106.1840（10）°, V = 2.5606（3） nm^3, Dc = 1.366 g/cm^3, Z = 8, F（000） = 1104, μ（MoKα= 3.182 mm^-1, S = 0.837, the final R = 0.0460 and wR = 0.1033. Crystal X-ray diffraction analysis for 2c showed that its ring skeleton adopts [3333] conformation, in which the OH group presents at the side-exo position and the other one at the corner carbon. The 1H NMR data of 2 showed that 1-corner-R-2-side-exo-OH [3333] and 1-corner-OH-2-side-exo-R [3333] conformations coexist in dynamic equilibrium in the solution, but only the former presents in the crystal.
文摘Conformation analysis of the model compounds for tunicamycin V and its natural donor substrate, UDP-N-acetylglucose, is performed to reveal the detail of the inhibition process.
文摘Triadimefon(TDM)and cyproconazole(CPZ)are two triazoles widely used as fungicides.Several azoles were synthe-sised starting from commercial TDM and CPZ.The compounds were evaluated against phytopathogenic filamentous fungi,including Aspergillus fumigatus(AF),A.niger(AN),A.ustus(AU),A.japonicus(AJ),A.terreus(AT),Fusarium oxyspo-rum and Botrytis cinerea isolated from grapevine in the province of San Juan,Argentina.Three of the synthesised compounds(1-(Biphenyl-4-yloxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one,1;2-(Biphenyl-4-yl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol,3;3-Cyclopropyl-2-(4’-fluorobiphenyl-4-yl)-1-(1H-1,2,4-triazol1-yl)butan-2-ol,4)presented remarkable in vitro fungicidal properties,with better effects than TDM and CPZ on some of the target fungi.Cytotoxicity was assessed using human lung fibroblasts MRC5.Derivative 1,with IC50 values of 389.4μM,was less toxic towards MRC-5 human lung fibroblasts than commercial TDM(248.5μM)and CPZ(267.4μM).Docking analysis and molecular dynamics simulations suggest that the compounds present the same interaction in the binding pocket of the CYP51B enzyme and with the same amino acids as CPZ.The derivatives investigated could be considered broad-spectrum but with some selectivity towards imperfect fungi.
文摘The paper first analyzes the achievement of BOE＇s merging case and substantiates its success, then focuses on the strategy analysis of merger of the BOE, including the guidelines, merging way, strategic overall arrangement, culture conformity, financial guarantee etc., in a bid to offer valuable experience and reference function for the Chinese enterprises.
文摘The crystal structure of the title compound ((C 6H 5CONC 6H 4S) 2, M r =229) has been determined by X ray diffraction analysis. The crystal belongs to triclinic space group P 1 with cell parameters: a=7.957(4), b=11.570(7), c=12 335(6), α=76.68(4), β=81.48(4), γ=87.26(4)°, V=1092.9 3, Z=2, D c =1 39g/cm 3, F(000)=476, μ (Mo Kα )=2.7mm -1 . The final R factor is 0.0373 for 3764 observed reflections. The result of X ray diffraction analysis indicates that all of these single bond lengths are obviously shorter than that of standard single bond. Those atoms might take part in a conjugate system. The electrons for sp 3 hybridized S(1) and S(2) move toward two sides and the densities of electronic cloud among them are reduced and can be easily broken. The obtained results can explain the reaction mechanism of the title compound.
基金Supported by the National Natural Science Foundation of China(Nos.21263019 and 51364038)
文摘A new coordination compound Zn（2,4＇-bpt）2（H2O）（1） based on the versatile ligand 2,4＇-Hbpt（2,4？-Hbpt = 3-（2-pyridyl）-5-（4-pyridyl）-1H-1,2,4-triazole） was prepared by hydrothermal reactions. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, X-ray powder diffraction, IR spectrum analysis and thermogravimetric analysis. Single-crystal X-ray diffraction analysis indicates that the complex belongs to monoclinic system, space group C2/c with a = 23.877（3）, b = 0.7483（9）, c = 1.2492（2） A, b = 92.681（2）°, V = 2230.6（4） A^3, Z = 4, Dc = 1.572 g/cm^3, m = 1.143 mm^-1, Mr = 527.85 and F（000） = 1080. The final R = 0.0581 and wR = 0.0898 with I 〉 2s（I）. 1 is a 0D motif which is connected by hydrogen bonds to form a corrugated 1D pattern. In addition, 1 shows strong photoluminescent emissions in the solid state at room temperature which can be used as potential optical materials. Theoretical calculations based on density functional theory（DFT） were employed in order to explicate the stability and chemical reactivity of 2,4＇-Hbpt with different conformations. The results indicated that conformation I is more stable and prior to coordination in the reactions.
基金supported by the National Key R&D Program of China (Nos. 2016YFA0400900, 2017YFA0505300)the Instrument Developing Project of the Chinese Academy of Sciences (No. YZ201564)
文摘Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which is independent of fluorophore concentrations, scattering and bleaching, is a suitable tool to analyze membrane proteins in a single cell. Ferroportin（FPN）, a multi-ion exporter in vertebrates, was modulated by metal ions with unknown mechanism. Herein, we fused green fluorescence protein on Cterminal of FPN（FPN-eGFP） and applied fluorescence lifetime to monitor conformation changes of FPN in a live cell. The fluorescence lifetime distribution showed a shift to shorter lifetime upon Mn^（2＋） treatment,suggesting a preference conformation of FPN in Mn^（2＋） exposure. It is also observed that the lifetime（rather than intensity） measurement was not strongly influenced by laser power. The observed fluorescence lifetime changes of FPN-eGFP upon Mn^（2＋） treatments indicated that extracellular metal ions can modulate FPN through conformation exchanges between several different states.
文摘The need for the analysis of modern businesses is rapidly increasing as the supporting enterprise systems generate more and more data.This data can be extremely valuable for executing organizations because the data allows constant monitoring,analyzing,and improving the underlying processes,which leads to the reduction of cost and the improvement of the quality.Process mining is a useful technique for analyzing enterprise systems by using an event log that contains behaviours.This research focuses on the process discovery and refinement using real-life event log data collected from a large multinational organization that deals with coatings and paints.By investigating and analyzing their order handling pro-cesses,this study aims at learning a model that gives insight inspection of the processes and performance analysis.Furthermore,the animation is also performed for the better inspection,diagnostics,and compliance-related questions to specify the system.The configuration of the system and the conformance checking for further enhancement is also addressed in this research.To achieve the objectives,this research uses process mining techniques,i.e.process discovery in the form of formal Petri nets models with the help of process maps,and process refinement through conformance checking and enhancement.Initially,the identified executed process is reconstructed by using the process discovery techniques.Following the reconstruction,we perform a deep analysis for the underlying process to ensure the process improvement and redesigning.Finally,some recommendations are made to improve the enterprise management system processes.
文摘The crystal structure of the title compound cis 2 (P, P Diethoxy)phosphono( m nitro)benzyloxy 4 Phenyl 5,5 Dimethyl 1,3,2 Dioxaphosphorinane 2 Sulfide, C 22 H 29 NO 8P 2S, was determined by single crystal X ray diffraction. It crystallizes in the monoclinic system, space group P2 1/c, with M r=529.49, a=9.888(2), b=20.831(4), c=12.797(3) , β=94.42(3)°, V=2628(1) 3, Z=4, D x =1.338 g/cm 3 , λ=0.71073 , μ =0.2796 mm 1 and F(000) =556. The structure was solved by direct methods. The final R factor is 0.052 and R w is 0.057 for 1793 unique observed reflections I≥3σ(I) . A cis configuration and a preferred chair conformation for the molecule have been established by X ray diffraction analysis. The results presented also give a good explanation to the correlation between the configurational assignments and the regularity in the chemical shifts of C 4-H and 31 P NMR.
基金the National Natural Science Foundation of China(31270104)the NSFC-Shandong Joint Fund for Marine Science Research Centers(U1606403)+2 种基金the Oceanographic Data Center at IOCAS.T.K.and A.M.thank the National Research,Development and Innovation Office(NKFI K120181 and FK134653)the Governmental Information-Technology Development Agency(KIFU for CPU time)B.-G.W.also acknowledged the support of the Taishan Scholar project from Shandong province.
文摘Chemical investigation of Beouverio felina,a marine-derived entomopathogenic fungus,obtained two new destruxin hexadepsipeptides(1 and 2)containing an/.-Ala^(5)residue instead of the usual A/-Me-L-Ala^(5).Interestingly,the presence of the/.-Ala^(5)residue enabled two slowly-exchanging solution conformers with cis/trons(ILE^(3))-(A/-Me-Val^(4))amide bond for 1 and 2 with 1.5:1 and 1:1 cis/trans ratios,respectively,while only the conformer with c/s amide bond was found in the solid-state.The solution and solid-state conformers were studied by NMR,X-ray diffraction and solution and solid-state ECD measurements,as well as by TDDFT-ECD calculations.Structural(conformational)parameter-activity correlations suggested that the extended destruxin geometry with the preferred c/s(ILE^(3))-(A/-Me-Val^(4))bond probably resulted in improved bioactivity and reduced toxicity for the destruxin class.This was the first report on the interconversion phenomenon of cis/trans amide bonds of destruxin class,which could give insights in the development of bioactive destruxin agents with lower toxicity.
基金financial support from National Natural Science Foundation of China(22071174,22371204)Ministry of Education,Singapore(grant no.A-8000054-01-00)Q.Yao acknowledges the financial support from Fundamental Research Funds for the Central Universities.
文摘For nanochemistry, precise manipulation of nanoscalestructures and the accompanying chemical properties atatomic precision is one of the greatest challenges today. Thescientific community strives to develop and design customizednanomaterials, while molecular interactions often serve as key toolsor probes for this atomically precise undertaking. In thisPerspective, metal nanoclusters, especially gold nanoclusters,serve as a good platform for understanding such nanoscaleinteractions. These nanoclusters often have a core size of about 2nm, a defined number of core metal atoms, and protecting ligandswith known crystal structure. The atomically precise structure ofmetal nanoclusters allows us to discuss how the molecularinteractions facilitate the systematic modification and functionalization of nanoclusters from their inner core, through the ligandshell, to the external assembly. Interestingly, the atomic packing structure of the nanocluster core can be affected by forces on thesurface. After discussing the core structure, we examine various atomic-level strategies to enhance their photoluminescent quantumyield and improve nanoclusters’ catalytic performance. Beyond the single cluster level, various attractive or repulsive molecularinteractions have been employed to engineer the self-assembly behavior and thus packing morphology of metal nanoclusters. Themethodological and fundamental insights systemized in this review should be useful for customizing the cluster structure andassembly patterns at the atomic level.
文摘A DFT calculations are carried out at UB3LYP/6-311＋ ＋G （3df, 2p） levels of theory to study electrocyclic thermal cleavage of four （R） derivatives of unsaturated bicyclic diaziridines, Ix-R, to produce corresponding （Z） and （E） azomethine imides （2X-Z, 2X-E, 3X-Z and 3X-E）, where X=H, Me, t-Bu and Ph. Cleavage of 1X-R series to form the most stable 3X-Z product, （path 2） is found the favored procedure because of delocalized negative charge on five atoms and lower steric effect in related transition state. According to IRC calculations in paths 1 and 2, C6--N1 bond is cleaved before the rate determinating step （transition state）. The stability of unsaturated bicyclic diaziridines and their corresponding （Z） and （E） azomethine imides is in the following order in gas phase and chloroform, tetrahydrofuran, and acetone solvents： 3X-Z〈3X-F〈2X-Z 〈2X-E 〈 1X-R 〈 1X-S.
文摘5, 10, 15-Triphenyl-20-{2-[alpha-(adenine-9) acetylamino]} phenyl porphyrin (1), 5,10,15-triphenyl-20-{2-[alpha-(cytosine-]}acetylamino]} phenyl porphyrin (2), 5, 10, 15-triphenyl-20-{4-[alpha(cytosine-1)ethoxy]} I I phenyl porphyrin (3) and their zinc complexes Zn-1, Zn-2 and Zn-3 have been prepared and characterized by H-1 NMR spectra, elemental analyses, electronic absorption spectra and mass spectra (FAB). Intramolecular pi-pi interactions and intramolecular metal-pi interaction for 1, 2, Zn-1, and Zn-2 have been investigated by several methods. H-1 NMR studies demonstrate that the porphyrin pi-system in 1 and 2 is parallel to the adenine and the cytosine aromatic ring, respectively. The electronic absorption spectral properties of free porphyrin derivatives and their zinc complexes have been compared with those of H2TPP and ZnTPP. The results show that the UV-vis spectra of 1 and 2 are the same as that of H2TPP, whereas the spectra of their zinc complexes show 7 nm red shifts of the Soret bands compared to that of ZnTPP. The emission spectra of Zn-1 and Zn-2 are independent of excitation wavelength. From combination of the evidence of absorption and emission spectra it is suggested the existence of intramolecular metal-pi interaction in Zn-1 and Zn-2. The results of conformational analysis agreed quite nicely with that of experiments, thus it was further to validate the experimental conclusions.
文摘Biocatalysts are intrinsically reactive and hence their operational stability is of vital significance for any bioprocess. The setback in biocatalyst stability has been tackled from diverse prospects. Inherently, stable biocatalysts are markedly realized and a regular attempt is being made to seek out new organisms that harbor them. Here, we analyzed the industrial biocatalyst lipase A （Native） of Bacillus subtilis and its six thermostable mutants （2M, 3M, 4M, 6M, 9M and 12M） computationally using conformational sampling technique. Consequently, the various structural events deciphering thermostability like root mean square deviation, root mean square fluctuation, radius of gyration and polar surface area showed mutant 12M to be highly stable with statistical validation. Besides, static model analysis involving intra-molecular interactions, secondary structure, solvent accessibility, hydrogen bond pattern, simulated thermal denaturation and desolvation energy also supported 12M comparatively. Of note, the presence of high secondary structural rigidity and hydrogen bonds increased thermostability and functionality of 12M, thus selecting it as a best template for designing thermostable lipases in future. Also, this study has a significant implication toward a better understanding of conformational sampling in enzyme catalysis and enzyme engineering.
