The mechanisms for CH3- and CH_4-elimination in the gas phase reaction of ground-state Zr with 2-butyne has been investigated in detail using B3LYP method.For the elimination of CH3,two mechanisms which are similar to...The mechanisms for CH3- and CH_4-elimination in the gas phase reaction of ground-state Zr with 2-butyne has been investigated in detail using B3LYP method.For the elimination of CH3,two mechanisms which are similar to those previously found for the reactions of Y and Zr with propyne are identified.The mechanism for the elimination of CH_4 was revealed as：Zr ＋ CH3C≡CCH_3→π-complex→TS（H-migration）→HZr-（H2CCC）-CH3→TS（C-C insertion）→（H2CCC）-HZr-CH3→TS（H-migration）→CH4＋ ZrC3H2.展开更多
The study on membrane proteins is an important challenge mainly because of their very poor solubility in various solvents.The traditional recombinant expression strategy and the native chemical ligation method both ha...The study on membrane proteins is an important challenge mainly because of their very poor solubility in various solvents.The traditional recombinant expression strategy and the native chemical ligation method both have difficulty in generating sufficient amounts of desired proteins with high efficiency.Previous studies have shown that multiply fluorinated alcohols exhibit good ability to dissolve difficult peptide sequences,especially hexafluoro-2-propanol (HFIP).In the present study we systematically studied the capability of solvents containing different percentage of HFIP in dissolving transmembrane peptides.Through both HPLC and UV analyses we concluded that 60% HFIP/8 M urea constituted a good solvent system.In this solvent system we also optimized conditions to perform native chemical ligation (NCL).Under the optimized conditions we successfully achieved NCL’s for both dipeptide formation and the synthesis of a model protein (Trifolitoxin).These results suggested that HFIP was a potential cosolvent that could be used in the ligation of poorly soluble peptides for the generation of membrane proteins.展开更多
基金supported by the General Programs of the Applied Basic Research of Science and Technology, Department of Yunnan Province(Nos.2008ZC095 and 2007B066M).
文摘The mechanisms for CH3- and CH_4-elimination in the gas phase reaction of ground-state Zr with 2-butyne has been investigated in detail using B3LYP method.For the elimination of CH3,two mechanisms which are similar to those previously found for the reactions of Y and Zr with propyne are identified.The mechanism for the elimination of CH_4 was revealed as：Zr ＋ CH3C≡CCH_3→π-complex→TS（H-migration）→HZr-（H2CCC）-CH3→TS（C-C insertion）→（H2CCC）-HZr-CH3→TS（H-migration）→CH4＋ ZrC3H2.
基金financially supported by the National Natural Science Foundation of China (20932006 & 20802040)
文摘The study on membrane proteins is an important challenge mainly because of their very poor solubility in various solvents.The traditional recombinant expression strategy and the native chemical ligation method both have difficulty in generating sufficient amounts of desired proteins with high efficiency.Previous studies have shown that multiply fluorinated alcohols exhibit good ability to dissolve difficult peptide sequences,especially hexafluoro-2-propanol (HFIP).In the present study we systematically studied the capability of solvents containing different percentage of HFIP in dissolving transmembrane peptides.Through both HPLC and UV analyses we concluded that 60% HFIP/8 M urea constituted a good solvent system.In this solvent system we also optimized conditions to perform native chemical ligation (NCL).Under the optimized conditions we successfully achieved NCL’s for both dipeptide formation and the synthesis of a model protein (Trifolitoxin).These results suggested that HFIP was a potential cosolvent that could be used in the ligation of poorly soluble peptides for the generation of membrane proteins.
