Two kinds of saponins have been investigated by negative electrospray ionization(NESI) mass spectrometry. Under ESI conditions, the - ions of saponins were observed which provide the molecular weights of saponins. The...Two kinds of saponins have been investigated by negative electrospray ionization(NESI) mass spectrometry. Under ESI conditions, the - ions of saponins were observed which provide the molecular weights of saponins. The fragment pathways of - ions of these two saponins depend on their structures. For steroidic saponins, - ion only produces the fragment ions by the losses of sugar units. For oleanolic saponins, - ion yields the cross ring ions as well as the fragment ions by the losses of sugar units. Moreover, the abundance of the former is higher than that of the latter. The characteristic fragments are used to provide the sequence and some linkage information of sugar moieties of saponins. Especially, their fragment difference strongly depends on the linkage between the aglycone and the sugar moieties.展开更多
Electrospray ionization(ESI) and tandem mass spectrometry have been used to investigate the gas phase interactions of five metal ions and seven dipeptides. For silver ion, two complexes( + and +) were obtained as well...Electrospray ionization(ESI) and tandem mass spectrometry have been used to investigate the gas phase interactions of five metal ions and seven dipeptides. For silver ion, two complexes( + and +) were obtained as well as the one complex ( +) for transition metal ions. Upon collision activation, there is an obvious difference in MS/MS data between metal ion complex and the protonated molecule. The fragment pathway of each complex is related to the structures of dipeptide and the nature of metal ion which suggest that there are several interaction between the metal ions and dipeptides in gas phase.展开更多
In this paper,the noncovalent interactions between α1-acid glycoprotein（AAG） and the drugs,such as ketoprofen（KP） and anisodine hydrobromide（AN） were studied by using electrospray ion trap mass spectrometry met...In this paper,the noncovalent interactions between α1-acid glycoprotein（AAG） and the drugs,such as ketoprofen（KP） and anisodine hydrobromide（AN） were studied by using electrospray ion trap mass spectrometry method.The results show that both of the drugs had a strong coalescent interaction with AAG,the（dissociation） constants（Kd） and the apparent stoichiometric ratio of noncovalent complexes AN-AAG were（1.75×10-3 mol/L） and 1∶7,and those for KP-AAG complex were 4.95×10-4 mol/L and 1∶4,respectively.According to the thermodynamic parameters of the noncoralent complexes,the main sorts of binding force were static-electricity gravitation for KP-AAG and Van der Waals force for AN-AAG,respectively. The experiment proves that ESI-MS technology as a new method for studying the drug-protein noncoralent binding can offer some advantages in sensitivity,speed,accuracy and directness particularly in the determination of the stoichiormetry of the complex compared to other well-established methods such as circular dichroism and fluorescence spectroscopy,etc.展开更多
文摘Two kinds of saponins have been investigated by negative electrospray ionization(NESI) mass spectrometry. Under ESI conditions, the - ions of saponins were observed which provide the molecular weights of saponins. The fragment pathways of - ions of these two saponins depend on their structures. For steroidic saponins, - ion only produces the fragment ions by the losses of sugar units. For oleanolic saponins, - ion yields the cross ring ions as well as the fragment ions by the losses of sugar units. Moreover, the abundance of the former is higher than that of the latter. The characteristic fragments are used to provide the sequence and some linkage information of sugar moieties of saponins. Especially, their fragment difference strongly depends on the linkage between the aglycone and the sugar moieties.
文摘Electrospray ionization(ESI) and tandem mass spectrometry have been used to investigate the gas phase interactions of five metal ions and seven dipeptides. For silver ion, two complexes( + and +) were obtained as well as the one complex ( +) for transition metal ions. Upon collision activation, there is an obvious difference in MS/MS data between metal ion complex and the protonated molecule. The fragment pathway of each complex is related to the structures of dipeptide and the nature of metal ion which suggest that there are several interaction between the metal ions and dipeptides in gas phase.
文摘In this paper,the noncovalent interactions between α1-acid glycoprotein（AAG） and the drugs,such as ketoprofen（KP） and anisodine hydrobromide（AN） were studied by using electrospray ion trap mass spectrometry method.The results show that both of the drugs had a strong coalescent interaction with AAG,the（dissociation） constants（Kd） and the apparent stoichiometric ratio of noncovalent complexes AN-AAG were（1.75×10-3 mol/L） and 1∶7,and those for KP-AAG complex were 4.95×10-4 mol/L and 1∶4,respectively.According to the thermodynamic parameters of the noncoralent complexes,the main sorts of binding force were static-electricity gravitation for KP-AAG and Van der Waals force for AN-AAG,respectively. The experiment proves that ESI-MS technology as a new method for studying the drug-protein noncoralent binding can offer some advantages in sensitivity,speed,accuracy and directness particularly in the determination of the stoichiormetry of the complex compared to other well-established methods such as circular dichroism and fluorescence spectroscopy,etc.
