The structures and stabilities of these still experimentally unknown CHnCl3-nO2-Li^＋ and CFnCl3-nO2-Li^＋ ions have been theoretically investigated by ab initio molecular orbital theory and density functional theory ...The structures and stabilities of these still experimentally unknown CHnCl3-nO2-Li^＋ and CFnCl3-nO2-Li^＋ ions have been theoretically investigated by ab initio molecular orbital theory and density functional theory （DFT） in conjunction with the 6-311G（d,p）, 6-311 ＋G（d,p）, 6-311 ＋G（2d,p） and 6-311 ＋G（2df,2p） basis sets. The optimized geometries, chemical bonding and NBO analysis indicate that these complexes of CHnCl3-nO2-Li^＋ and CFnCl3-nO2- Li^＋ exist as ion-dipole molecules. The calculated affinity energies of these species exceed 41.9 kJ/mol, which are large enough to suggest the possibility that these title complexes could be detected as stable species in gas phase by Li^＋ ion attachment mass spectrometry.展开更多
为全面理解兔肉品质的形成过程,利用偶氮二异丁脒盐酸盐(2,2’-azobis(2-amidinopropane)dihydrochloride,AAPH)的热分解作用生成过氧自由基(ROO·)诱导兔肉肌浆蛋白氧化,通过AAPH处理后兔肉肌浆蛋白中高铁肌红蛋白相对含量、超铁...为全面理解兔肉品质的形成过程,利用偶氮二异丁脒盐酸盐(2,2’-azobis(2-amidinopropane)dihydrochloride,AAPH)的热分解作用生成过氧自由基(ROO·)诱导兔肉肌浆蛋白氧化,通过AAPH处理后兔肉肌浆蛋白中高铁肌红蛋白相对含量、超铁肌红蛋白浓度、羰基含量、总巯基含量以及肌浆蛋白表面疏水性、粒度、浊度和溶解性测定,肌浆蛋白十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)和内源荧光光谱分析,研究ROO·胁迫肌浆蛋白氧化聚集机制。结果表明,随着AAPH浓度的升高,高铁肌红蛋白和超铁肌红蛋白相对含量显著增加(P<0.05),蛋白质羰基含量显著增加(P<0.05),总巯基含量显著下降(P<0.05)。内源荧光光谱和表面疏水性分析结果表明ROO·可以引起肌浆蛋白的去折叠和疏水基团暴露。SDS-PAGE分析结果表明ROO·可以导致肌浆蛋白二硫键交联。此外,随着AAPH浓度的增大,肌浆蛋白粒度和浊度呈现出逐渐增大的趋势,表明ROO·可以引发肌浆蛋白的聚集。疏水相互作用和二硫键交联是ROO·胁迫肌浆蛋白聚集的主要作用力。ROO·不仅可以直接引发肌浆蛋白聚集,还可以通过影响肌红蛋白诱导氧化体系促进肌浆蛋白交联聚集。展开更多
Nucleoside analogues play an important role in the development of antitumor and antiviral agents. Specific sugar modified pyranonucleosides, like the keto and exocyclic methylene nucleosides, have been studied for the...Nucleoside analogues play an important role in the development of antitumor and antiviral agents. Specific sugar modified pyranonucleosides, like the keto and exocyclic methylene nucleosides, have been studied for their biological properties, but there is little information regarding their antioxidant activity. The present study reports the antioxidant activity of a series of α,β-unsaturated 2’- or 4’ - keto and exomethylene 5’-hydroxymethyl-lacking pyranonucleosides. The antioxidant activity was evaluated using an in vitro assay which is based on the capacity to protect DNA strand scission induced by peroxyl radicals (ROO?). The majority of the tested nucleoside analogues exhibit potent antioxidant properties against ROO? radicals. We conclude that the presence of a carbon-carbon double bond at α,β-disposition to exomethylene group at position 2 of the sugar moiety and the substitution of thymine with uracil improves the antioxidant capacity of these analogues.展开更多
基金Project supported by the National Natural Science Foundation of China and the Center for Computational Science, Hefei Institutes of Physical Science （No. 0330405002）.
文摘The structures and stabilities of these still experimentally unknown CHnCl3-nO2-Li^＋ and CFnCl3-nO2-Li^＋ ions have been theoretically investigated by ab initio molecular orbital theory and density functional theory （DFT） in conjunction with the 6-311G（d,p）, 6-311 ＋G（d,p）, 6-311 ＋G（2d,p） and 6-311 ＋G（2df,2p） basis sets. The optimized geometries, chemical bonding and NBO analysis indicate that these complexes of CHnCl3-nO2-Li^＋ and CFnCl3-nO2- Li^＋ exist as ion-dipole molecules. The calculated affinity energies of these species exceed 41.9 kJ/mol, which are large enough to suggest the possibility that these title complexes could be detected as stable species in gas phase by Li^＋ ion attachment mass spectrometry.
文摘为全面理解兔肉品质的形成过程,利用偶氮二异丁脒盐酸盐(2,2’-azobis(2-amidinopropane)dihydrochloride,AAPH)的热分解作用生成过氧自由基(ROO·)诱导兔肉肌浆蛋白氧化,通过AAPH处理后兔肉肌浆蛋白中高铁肌红蛋白相对含量、超铁肌红蛋白浓度、羰基含量、总巯基含量以及肌浆蛋白表面疏水性、粒度、浊度和溶解性测定,肌浆蛋白十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)和内源荧光光谱分析,研究ROO·胁迫肌浆蛋白氧化聚集机制。结果表明,随着AAPH浓度的升高,高铁肌红蛋白和超铁肌红蛋白相对含量显著增加(P<0.05),蛋白质羰基含量显著增加(P<0.05),总巯基含量显著下降(P<0.05)。内源荧光光谱和表面疏水性分析结果表明ROO·可以引起肌浆蛋白的去折叠和疏水基团暴露。SDS-PAGE分析结果表明ROO·可以导致肌浆蛋白二硫键交联。此外,随着AAPH浓度的增大,肌浆蛋白粒度和浊度呈现出逐渐增大的趋势,表明ROO·可以引发肌浆蛋白的聚集。疏水相互作用和二硫键交联是ROO·胁迫肌浆蛋白聚集的主要作用力。ROO·不仅可以直接引发肌浆蛋白聚集,还可以通过影响肌红蛋白诱导氧化体系促进肌浆蛋白交联聚集。
文摘Nucleoside analogues play an important role in the development of antitumor and antiviral agents. Specific sugar modified pyranonucleosides, like the keto and exocyclic methylene nucleosides, have been studied for their biological properties, but there is little information regarding their antioxidant activity. The present study reports the antioxidant activity of a series of α,β-unsaturated 2’- or 4’ - keto and exomethylene 5’-hydroxymethyl-lacking pyranonucleosides. The antioxidant activity was evaluated using an in vitro assay which is based on the capacity to protect DNA strand scission induced by peroxyl radicals (ROO?). The majority of the tested nucleoside analogues exhibit potent antioxidant properties against ROO? radicals. We conclude that the presence of a carbon-carbon double bond at α,β-disposition to exomethylene group at position 2 of the sugar moiety and the substitution of thymine with uracil improves the antioxidant capacity of these analogues.
