ABSTRACT
Differences of protonated and lithiated leucine-enkephalin(LE) were investigated by hydrogen deuterium exchange-mass spectrometry(HDX-MS) combined with quantum chemistry calculation. The results revealed that the protonated ions possessed very high product yield with all hydrogen atoms being exchanged, while the reaction of lithiated LE stopped after exchanging five hydrogen atoms in the same experimental conditions. The different HDX behaviours probably indicated their conformational differences. To further clarify the experimental results, the most stable conformations of protonated and lithiated leucine-enkephalin were calculated by density functional theory. It was found that terminal amino group was the most thermodynamically stable protonation site,while Li+in coordination of four carbonyl oxygen atoms formed the most favourable lithiated LE. The reaction field reduction of lithium LE was probably due to the less acidity of hydrogen atoms and the increasing rigid conformation change induced by lithium ion.
ABSTRACT
Objective To develop a portable ventilation device to cool and dehumidify for the astronauts who work or move dressed in spacesuit in the atmospheric environment on the ground.Methods Based on the requirement which the astronauts need when they are dressed in spacesuit on the ground,the overall design project has been brought forward,which expounds the design scheme of DC brushless centrifugal fan,power supply,regulation of blowing rate,intelligent monitor on system parameters,organic light-emitting diode(OLED)display,device configuration,software,and so on.Results The portable device for spacesuit ventilation and heat-regulation,which has been developed,can work stably and safely.It has convenient operation mode and practical human-machine interface.Meanwhile,the device has compact configuration.It is light and portable.Conclusion The portable device for spacesuit ventilation and heat-regulation carry out the portable ventilation and heat-regulation for the astronauts of China dressed in spacesuit dress for the first time.It also fulfils the spacesuit dryness after use and usual maintenance.