PBOND is a web server that predicts the conformation of the peptide bond between any two amino acids. PBOND classifies the peptide bonds into one out of four classes, namely cis imide （cis-Pro）, cis amide （cis-non...PBOND is a web server that predicts the conformation of the peptide bond between any two amino acids. PBOND classifies the peptide bonds into one out of four classes, namely cis imide （cis-Pro）, cis amide （cis-nonPro）, trans imide （trans-Pro） and trans amide （trans-nonPro）. Moreover, for every prediction a reliability index is computed. The underlying structure of the server consists of three stages： （1） feature extraction, （2） feature selection and （3） peptide bond classification. PBOND can handle both single sequences as well as multiple sequences for batch processing. The predictions can either be directly downloaded from the web site or returned via e-mail. The PBOND web server is freely available at http：//195.251.198.21/pbond.html.展开更多
In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photo...In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photoresponsive beha-vior of the green, environment friendly product was investigated. The end hydroxyl group of lignin was modified with the chromophoric systems by DCC coupling. The chromophoric systems as well as the chromophore-bound biopolymer core systems were purified by column chromatography. The products were characterized by UV-visible, fluorescence, FT-IR and NMR spectroscopic methods. The results of the studies show that incorporation of the chromophoric system on to the lignin core enhanced the light absorption, emission and light stabilization properties of the chromophoric system. The light fastening properties of chromophoric system and the modified product were compared. It shows that stability of the chromophoric system greatly enhanced on attaching to the polymeric system. The trans-cis photoisomerisation and the reverse cis-trans thermal conversions were also assisted by the lignin core. The remarkable stability on irradiation shows that this is a novel photoresponsive system with excellent light fastening properties which would find application in coating materials, dyes, paints, inks, therapeutic agents and many more.展开更多
AIM： To examine whether trans-10,cis-12 CLA （t10C12） or cis-9,trans-11 CLA （c9t11） inhibits heregulin （HRG）-β- stimulated cell growth and HRG-β-ErbB3 signaling in HT-29 cells. METHODS： We cultured HT-29 cell...AIM： To examine whether trans-10,cis-12 CLA （t10C12） or cis-9,trans-11 CLA （c9t11） inhibits heregulin （HRG）-β- stimulated cell growth and HRG-β-ErbB3 signaling in HT-29 cells. METHODS： We cultured HT-29 cells in the absence or presence of the CLA isomers and/or the ErbB3 ligand HRG-β. MTT assay, [^3H]thymidine incorporation, Annexin V staining, RT-PCR, Western blotting, immunoprecipitation, and in vitro kinase assay were performed. RESULTS： HRG-β increased cell growth, but did not prevent DNA t10c12-induced growth inhibition. T10C12 inhibited DNA synthesis and induced apoptosis of HT-29 cells, whereas c9t11 had no effect. T10c12 decreased the levels of ErbB1, ErbB2, and ErbB3 proteins and transcripts in a dose-dependent manner, whereas c9t11 had no effect. Immunoprecipitation/ Western blot studies revealed that t10c12 inhibited HRG- β-stimulated phosphorylation of ErbB3, recruitment of the p85 subunit of phosphoinositide 3-kinase （PI3K） to ErbB3, ErbB3-associated PI3K activities, and phosphorylation of Akt. However, c9t11 had no effect on phospho Aid： levels. Neither t10c12 nor c9t11 had any effect on HRG-β-induced phosphorylation of ERK-1/2. CONCLUSION： These results indicate that the inhibition of HT-29 cell growth by t10c12 may be induced via its modulation of ErbB3 signaling leading to inhibition of Akt activation.展开更多
Two novel biscrown ethers with rigid cis/trans ethylene linker were synthesized via Wittig reaction in high yield （about 80%）. Their pure cisltrans-isomers were obtained by column chromatography separation. And thei...Two novel biscrown ethers with rigid cis/trans ethylene linker were synthesized via Wittig reaction in high yield （about 80%）. Their pure cisltrans-isomers were obtained by column chromatography separation. And their structure/configuration was confirmed by ^1H NMR,^ 13C NMR, ESI mass spectrum, elemental analysis and UV-vis speca＇a.展开更多
Objective: To determine the effect of cis-9, trans-1 1-conjugated linoleic acid on the cell cycle of mammary cancer cells (MCF-7) and the possible mechanism of the inhibitory effect of c9,t11-CLA. Methods: Using cell ...Objective: To determine the effect of cis-9, trans-1 1-conjugated linoleic acid on the cell cycle of mammary cancer cells (MCF-7) and the possible mechanism of the inhibitory effect of c9,t11-CLA. Methods: Using cell culture and immunocytochemical techniques, we examined the cell growth, DNA synthesis, expression of PCNA, cyclin A, B1, D1, p16ink4a and p21cip/waf1 of MCF-7 cells at various c9,t11-CLA concentrations (25μM, 50μM, 100μM and 200μM), at 24h and 48h. 96% ethand was used as negative control. Results: The cell growth and DNA synthesis of MCF-7 cells were inhibited by c9,t11-CLA. After treatment with various doses of c9,t11-CLA mentioned above for 8 days, the inhibition frequency was 27.18%, 35.43%, 91.05%, and 92.86%, respectively. Inhibitory effect of c9,t11-CLA on DNA synthesis (except for 25μM, 24h) was demonstrated by significantly less incorporation of 3H-TdR than the negative control (P<0.05 and P<0.01). To further investigate the influence of the cell cycle progression, we found that c9,t11-CLA may arrest the cell cycle of MCF-7 cells. Immunocytochemical staining demonstrated that incubation with different concentration of c9,t11-CLA at various times significantly decreased the expression of PCNA, Cyclin A, B1, D1 in MCF-7 cells compared to the negative control (P<0.01), whereas the expression of p16ink4a and p21cip/waf1, cyclin-dependent kinases inhibitors (CDKI), were increased. Conclusions: The cell growth and proliferation of MCF-7 cells is inhibited by c9,t11-CLA via blocking cell cycle, accompanying reduced expression of cyclin A, B1, D1 and enhanced expression of CDKI (p16ink4a and p21cip/waf1).展开更多
After the preparation of 1,4-bis（4,5-dihydro-lH-imidazol-2-yl）benzene（bdib）, a nitrogen heterocycle with potential coordination manners of both cis- and trans-configuration forms, three complexes, including cis-[...After the preparation of 1,4-bis（4,5-dihydro-lH-imidazol-2-yl）benzene（bdib）, a nitrogen heterocycle with potential coordination manners of both cis- and trans-configuration forms, three complexes, including cis-[Cuz（bdib ）2（/L-OCH3）2]Cl2·2MeOH（1）, trans-[Cu（bdib）（AcO）2]n（2）, and cis-[Ag2（bdib）2]（NO3）2.2H20（3）, were successfully self-assembled. Complexes 1 and 2 crystallized in the monoclinic system with P21/n space group and complex 3 in the triclinic system with P1 space group.展开更多
A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiol...A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiolane lactol 5 by SOCl2/DMF, followed by coupling with silylated N^4- acetylcytosine and deprotection. The overall yield was 42.6 % and 20,1%, respectively.展开更多
[(η5-C5H4Me)Mo(CO)2PPh3I] undergoes solid state transformation on the formation of a good pellet for FT IR measurement. There was a formation of the products mixture on pelleting using different diluents of group I m...[(η5-C5H4Me)Mo(CO)2PPh3I] undergoes solid state transformation on the formation of a good pellet for FT IR measurement. There was a formation of the products mixture on pelleting using different diluents of group I metal salts on either the cis or the trans isomer of the [(η5-C5H4Me)Mo(CO)2PPh3I] complex. The cis or the trans isomer gave the same IR spectra i.e. a mixture of cis and trans isomer of the complex. It does not matter the isomer started with in the course of solid state transformation reaction, an equilibrium ratio of 30/70 (trans/cis) will still be achieved. The solid state IR spectra show very strong peaks at νco 1957, 1947 and strong peaks at 1867, 1853 cm–1. The individual IR cis/trans isomer will therefore show at 1947 and 1853/1957 and 1867 cm–1. The solution IR spectra gave, cis = 1961, 1875 and trans = 1963, 1882 cm–1 in dry CHCl3. Hence, most of the solid state IR measurement of the organometallic complex of the type (η5-C5H4Me)Mo(CO)2(PPh3)I on pelleting will give isomer mixture.展开更多
A series of novel crown aldoxime ethers were synthesized,demonstrating notable thermal and hydrolysis stability.The showcased acid-catalyzed and photo-induced cis/trans isomerization,which enables orthogonal control o...A series of novel crown aldoxime ethers were synthesized,demonstrating notable thermal and hydrolysis stability.The showcased acid-catalyzed and photo-induced cis/trans isomerization,which enables orthogonal control over both vip complexation and the chiroptical effects of these crown aldoxime ethers,manifesting a regulation of complexation through isomerization at binding heteroatoms.展开更多
The dihydride cluster H_2O_(s_3)(CO)_(10) reacts with ethyne to give a cis-adduct [O_(s_3)H(μ,η~2-CH=CH_2)(CO)_(10)]. The high deuterated cluster D_2O_(s_3)(CO)_(10), the reaction of D_2O_(s_3)(CO)_(10)with ethyne C...The dihydride cluster H_2O_(s_3)(CO)_(10) reacts with ethyne to give a cis-adduct [O_(s_3)H(μ,η~2-CH=CH_2)(CO)_(10)]. The high deuterated cluster D_2O_(s_3)(CO)_(10), the reaction of D_2O_(s_3)(CO)_(10)with ethyne C_2H_2 to form the vinyl product cluster [O_(s_3)D(μ, η~2-CH=CHD)(CO)_(10)], and thereaction of H_2O_(s_3)(CO)_(10) with the deuterated ethyne C_2D_2 to form [O_(s_3)H(μ,η~2-CD=CDH)(CO)_(10)] have been reported primarily in this paper. The two cis-adducts undergo cis-trans-isomerization of μ,η~2-vinyl ligands under a small amount of the nucleophile pyridine. Usingthe combination of deuteration and dynamic ~1H,~2H NMR spectra, we report the experimen-tal evidence determined by the dynamic ~1H, ~2H NMR spectra, mechanism, and kinetic dataof the isomerization.展开更多
Photochemical and thermal isomerization of various azobenzenes was systematically investigated to understand the correlation between the molecular structure and trans → cis isomerization characteristics of azobenzene...Photochemical and thermal isomerization of various azobenzenes was systematically investigated to understand the correlation between the molecular structure and trans → cis isomerization characteristics of azobenzenes. A blue shift in π-π absorption band of ortho-alkylated azobenzenes （1o and 2o） was observed together with a reduction in molar extinction coefficient （e） in comparison with both meta-alkylated azobenzenes （4m and 5m） and 7p lacking the meta and ortho substituents. For orthoalkylated azobenzene, photochemical trans-to-cis isomerization and thermal back cis-to-trans isomerization in solution oc- curred slowly when compared with 4m, 5m and 7p. The half-life time of the cis form of 20 was found to be 380 h, which is about 8-50 times longer than those of comparable 4m, 5m （43-13 h） and 7p （7 h）. Furthermore, comparison of the molecular structure and isomerization characteristics of azobenzene thiol （20 and 5m） self-assembled monolayers on flat gold surfaces indicates that the trans-to-cis photoconversion in monolayer systems is influenced by steric hindrance and strong intermoleculax interaction between azobenzene units.展开更多
Photochemical and thermal isomerization of various azobenzenes was systematically investigated to understand the correlation between the molecular structure and transcis isomerization characteristics of azobenzenes....Photochemical and thermal isomerization of various azobenzenes was systematically investigated to understand the correlation between the molecular structure and transcis isomerization characteristics of azobenzenes.A blue shift in π-π* absorption band of ortho-alkylated azobenzenes(1o and 2o) was observed together with a reduction in molar extinction coefficient(ε) in comparison with both meta-alkylated azobenzenes(4m and 5m) and 7p lacking the meta and ortho substituents.For ortho-alkylated azobenzene,photochemical trans-to-cis isomerization and thermal back cis-to-trans isomerization in solution occurred slowly when compared with 4m,5m and 7p.The half-life time of the cis form of 2o was found to be 380 h,which is about 8-50 times longer than those of comparable 4m,5m(43-13 h) and 7p(7 h).Furthermore,comparison of the molecular structure and isomerization characteristics of azobenzene thiol(2o and 5m) self-assembled monolayers on flat gold surfaces indicates that the trans-to-cis photoconversion in monolayer systems is influenced by steric hindrance and strong intermolecular interaction between azobenzene units.展开更多
文摘PBOND is a web server that predicts the conformation of the peptide bond between any two amino acids. PBOND classifies the peptide bonds into one out of four classes, namely cis imide （cis-Pro）, cis amide （cis-nonPro）, trans imide （trans-Pro） and trans amide （trans-nonPro）. Moreover, for every prediction a reliability index is computed. The underlying structure of the server consists of three stages： （1） feature extraction, （2） feature selection and （3） peptide bond classification. PBOND can handle both single sequences as well as multiple sequences for batch processing. The predictions can either be directly downloaded from the web site or returned via e-mail. The PBOND web server is freely available at http：//195.251.198.21/pbond.html.
文摘In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photoresponsive beha-vior of the green, environment friendly product was investigated. The end hydroxyl group of lignin was modified with the chromophoric systems by DCC coupling. The chromophoric systems as well as the chromophore-bound biopolymer core systems were purified by column chromatography. The products were characterized by UV-visible, fluorescence, FT-IR and NMR spectroscopic methods. The results of the studies show that incorporation of the chromophoric system on to the lignin core enhanced the light absorption, emission and light stabilization properties of the chromophoric system. The light fastening properties of chromophoric system and the modified product were compared. It shows that stability of the chromophoric system greatly enhanced on attaching to the polymeric system. The trans-cis photoisomerisation and the reverse cis-trans thermal conversions were also assisted by the lignin core. The remarkable stability on irradiation shows that this is a novel photoresponsive system with excellent light fastening properties which would find application in coating materials, dyes, paints, inks, therapeutic agents and many more.
基金Supported byagrant of the Korea Health21 R and D Project, Ministry of Heath and Welfare, Republic of Korea, No. 02-PJ1-PG10-22003-0001
文摘AIM： To examine whether trans-10,cis-12 CLA （t10C12） or cis-9,trans-11 CLA （c9t11） inhibits heregulin （HRG）-β- stimulated cell growth and HRG-β-ErbB3 signaling in HT-29 cells. METHODS： We cultured HT-29 cells in the absence or presence of the CLA isomers and/or the ErbB3 ligand HRG-β. MTT assay, [^3H]thymidine incorporation, Annexin V staining, RT-PCR, Western blotting, immunoprecipitation, and in vitro kinase assay were performed. RESULTS： HRG-β increased cell growth, but did not prevent DNA t10c12-induced growth inhibition. T10C12 inhibited DNA synthesis and induced apoptosis of HT-29 cells, whereas c9t11 had no effect. T10c12 decreased the levels of ErbB1, ErbB2, and ErbB3 proteins and transcripts in a dose-dependent manner, whereas c9t11 had no effect. Immunoprecipitation/ Western blot studies revealed that t10c12 inhibited HRG- β-stimulated phosphorylation of ErbB3, recruitment of the p85 subunit of phosphoinositide 3-kinase （PI3K） to ErbB3, ErbB3-associated PI3K activities, and phosphorylation of Akt. However, c9t11 had no effect on phospho Aid： levels. Neither t10c12 nor c9t11 had any effect on HRG-β-induced phosphorylation of ERK-1/2. CONCLUSION： These results indicate that the inhibition of HT-29 cell growth by t10c12 may be induced via its modulation of ErbB3 signaling leading to inhibition of Akt activation.
基金National Natural Science Foundation of China （No. 20672038） Natural Science Foundation of Guangdong Province （No. 5005934）.
文摘Two novel biscrown ethers with rigid cis/trans ethylene linker were synthesized via Wittig reaction in high yield （about 80%）. Their pure cisltrans-isomers were obtained by column chromatography separation. And their structure/configuration was confirmed by ^1H NMR,^ 13C NMR, ESI mass spectrum, elemental analysis and UV-vis speca＇a.
基金This work was supported by the National Natural Science Foundation of China(No.39870661). Phone: (0086-451)-3641309 Fax: (0086-451)-3641253
文摘Objective: To determine the effect of cis-9, trans-1 1-conjugated linoleic acid on the cell cycle of mammary cancer cells (MCF-7) and the possible mechanism of the inhibitory effect of c9,t11-CLA. Methods: Using cell culture and immunocytochemical techniques, we examined the cell growth, DNA synthesis, expression of PCNA, cyclin A, B1, D1, p16ink4a and p21cip/waf1 of MCF-7 cells at various c9,t11-CLA concentrations (25μM, 50μM, 100μM and 200μM), at 24h and 48h. 96% ethand was used as negative control. Results: The cell growth and DNA synthesis of MCF-7 cells were inhibited by c9,t11-CLA. After treatment with various doses of c9,t11-CLA mentioned above for 8 days, the inhibition frequency was 27.18%, 35.43%, 91.05%, and 92.86%, respectively. Inhibitory effect of c9,t11-CLA on DNA synthesis (except for 25μM, 24h) was demonstrated by significantly less incorporation of 3H-TdR than the negative control (P<0.05 and P<0.01). To further investigate the influence of the cell cycle progression, we found that c9,t11-CLA may arrest the cell cycle of MCF-7 cells. Immunocytochemical staining demonstrated that incubation with different concentration of c9,t11-CLA at various times significantly decreased the expression of PCNA, Cyclin A, B1, D1 in MCF-7 cells compared to the negative control (P<0.01), whereas the expression of p16ink4a and p21cip/waf1, cyclin-dependent kinases inhibitors (CDKI), were increased. Conclusions: The cell growth and proliferation of MCF-7 cells is inhibited by c9,t11-CLA via blocking cell cycle, accompanying reduced expression of cyclin A, B1, D1 and enhanced expression of CDKI (p16ink4a and p21cip/waf1).
基金Supported by the National Natural Science Foundation of China(No.20771073)
文摘After the preparation of 1,4-bis（4,5-dihydro-lH-imidazol-2-yl）benzene（bdib）, a nitrogen heterocycle with potential coordination manners of both cis- and trans-configuration forms, three complexes, including cis-[Cuz（bdib ）2（/L-OCH3）2]Cl2·2MeOH（1）, trans-[Cu（bdib）（AcO）2]n（2）, and cis-[Ag2（bdib）2]（NO3）2.2H20（3）, were successfully self-assembled. Complexes 1 and 2 crystallized in the monoclinic system with P21/n space group and complex 3 in the triclinic system with P1 space group.
文摘A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiolane lactol 5 by SOCl2/DMF, followed by coupling with silylated N^4- acetylcytosine and deprotection. The overall yield was 42.6 % and 20,1%, respectively.
文摘[(η5-C5H4Me)Mo(CO)2PPh3I] undergoes solid state transformation on the formation of a good pellet for FT IR measurement. There was a formation of the products mixture on pelleting using different diluents of group I metal salts on either the cis or the trans isomer of the [(η5-C5H4Me)Mo(CO)2PPh3I] complex. The cis or the trans isomer gave the same IR spectra i.e. a mixture of cis and trans isomer of the complex. It does not matter the isomer started with in the course of solid state transformation reaction, an equilibrium ratio of 30/70 (trans/cis) will still be achieved. The solid state IR spectra show very strong peaks at νco 1957, 1947 and strong peaks at 1867, 1853 cm–1. The individual IR cis/trans isomer will therefore show at 1947 and 1853/1957 and 1867 cm–1. The solution IR spectra gave, cis = 1961, 1875 and trans = 1963, 1882 cm–1 in dry CHCl3. Hence, most of the solid state IR measurement of the organometallic complex of the type (η5-C5H4Me)Mo(CO)2(PPh3)I on pelleting will give isomer mixture.
基金support of the National Natural Science Foundation of China (Nos.22271201,92056116,22171194,22201194)the Science & Technology Department of Sichuan Province (Nos.2022YFH0095 and 2021ZYD0052)the Fundamental Research Funds for the Central Universities (No.20826041D4117)。
文摘A series of novel crown aldoxime ethers were synthesized,demonstrating notable thermal and hydrolysis stability.The showcased acid-catalyzed and photo-induced cis/trans isomerization,which enables orthogonal control over both vip complexation and the chiroptical effects of these crown aldoxime ethers,manifesting a regulation of complexation through isomerization at binding heteroatoms.
基金Project supported by the National Natural Science Foundation of China.
文摘The dihydride cluster H_2O_(s_3)(CO)_(10) reacts with ethyne to give a cis-adduct [O_(s_3)H(μ,η~2-CH=CH_2)(CO)_(10)]. The high deuterated cluster D_2O_(s_3)(CO)_(10), the reaction of D_2O_(s_3)(CO)_(10)with ethyne C_2H_2 to form the vinyl product cluster [O_(s_3)D(μ, η~2-CH=CHD)(CO)_(10)], and thereaction of H_2O_(s_3)(CO)_(10) with the deuterated ethyne C_2D_2 to form [O_(s_3)H(μ,η~2-CD=CDH)(CO)_(10)] have been reported primarily in this paper. The two cis-adducts undergo cis-trans-isomerization of μ,η~2-vinyl ligands under a small amount of the nucleophile pyridine. Usingthe combination of deuteration and dynamic ~1H,~2H NMR spectra, we report the experimen-tal evidence determined by the dynamic ~1H, ~2H NMR spectra, mechanism, and kinetic dataof the isomerization.
基金supported by the Global COE Program from the Ministry of Education,Culture,Sports,Science,and Technology of Japanese Government
文摘Photochemical and thermal isomerization of various azobenzenes was systematically investigated to understand the correlation between the molecular structure and trans → cis isomerization characteristics of azobenzenes. A blue shift in π-π absorption band of ortho-alkylated azobenzenes （1o and 2o） was observed together with a reduction in molar extinction coefficient （e） in comparison with both meta-alkylated azobenzenes （4m and 5m） and 7p lacking the meta and ortho substituents. For orthoalkylated azobenzene, photochemical trans-to-cis isomerization and thermal back cis-to-trans isomerization in solution oc- curred slowly when compared with 4m, 5m and 7p. The half-life time of the cis form of 20 was found to be 380 h, which is about 8-50 times longer than those of comparable 4m, 5m （43-13 h） and 7p （7 h）. Furthermore, comparison of the molecular structure and isomerization characteristics of azobenzene thiol （20 and 5m） self-assembled monolayers on flat gold surfaces indicates that the trans-to-cis photoconversion in monolayer systems is influenced by steric hindrance and strong intermoleculax interaction between azobenzene units.
文摘Photochemical and thermal isomerization of various azobenzenes was systematically investigated to understand the correlation between the molecular structure and transcis isomerization characteristics of azobenzenes.A blue shift in π-π* absorption band of ortho-alkylated azobenzenes(1o and 2o) was observed together with a reduction in molar extinction coefficient(ε) in comparison with both meta-alkylated azobenzenes(4m and 5m) and 7p lacking the meta and ortho substituents.For ortho-alkylated azobenzene,photochemical trans-to-cis isomerization and thermal back cis-to-trans isomerization in solution occurred slowly when compared with 4m,5m and 7p.The half-life time of the cis form of 2o was found to be 380 h,which is about 8-50 times longer than those of comparable 4m,5m(43-13 h) and 7p(7 h).Furthermore,comparison of the molecular structure and isomerization characteristics of azobenzene thiol(2o and 5m) self-assembled monolayers on flat gold surfaces indicates that the trans-to-cis photoconversion in monolayer systems is influenced by steric hindrance and strong intermolecular interaction between azobenzene units.
