In this study, the effects of lead ions(Pb^(2+)) on the conformations of leucine encephalin(LE) and methionine encephalin(ME) in gas phase were studied using hydrogen/deuterium exchange mass spectrometry(HDX-MS) and q...In this study, the effects of lead ions(Pb^(2+)) on the conformations of leucine encephalin(LE) and methionine encephalin(ME) in gas phase were studied using hydrogen/deuterium exchange mass spectrometry(HDX-MS) and quantum chemistry theoretical calculations at the molecular level. The HDX-MS result revealed that the complexes with the monovalent compounds [LE+Pb–H]+ and [ME+Pb–H]+had a 1:1 stoichiometric ratio, and different HDX reactivates were observed in a follow of [ME+H]+>[LE+H]+>[LE+Pb–H]+> [ME+Pb–H]+. Combining the collision-induced dissociation energies of the complexes and their HDX results, it was found that the more stable the complex, the harder it was for HDX. In addition, the favo-rable conformations of the complexes were obtained by theoretical calculations, revealing that the similar coordination type with diffe-rent bond lengths was obtained. Then, the proton affinity(PA) values of the optimized complexes were calculated to interpret the HDX observations, indicating that the higher the PA values, the more difficult it was for HDX. Overall, the experiments and theoretical calculations revealed that Pb^(2+) could induce conformational changes of LE and ME, and generate ME into a more rigid conformation than LE. The results will prompt further fundamental investigations on the conformational properties of LE/ME in coordination with Pb^(2+).展开更多
基金supported by the National Natural Science Foundation of China (Nos.22004074,21927805,21803013 and 21773035)the Public Welfare Fund Project of Ningbo City,China(No.202002N3113)+1 种基金the National Key Research and Development Program of China(No.2020YFF01014601)the K.C.Wong Magna Fund in Ningbo University,China.
文摘In this study, the effects of lead ions(Pb^(2+)) on the conformations of leucine encephalin(LE) and methionine encephalin(ME) in gas phase were studied using hydrogen/deuterium exchange mass spectrometry(HDX-MS) and quantum chemistry theoretical calculations at the molecular level. The HDX-MS result revealed that the complexes with the monovalent compounds [LE+Pb–H]+ and [ME+Pb–H]+had a 1:1 stoichiometric ratio, and different HDX reactivates were observed in a follow of [ME+H]+>[LE+H]+>[LE+Pb–H]+> [ME+Pb–H]+. Combining the collision-induced dissociation energies of the complexes and their HDX results, it was found that the more stable the complex, the harder it was for HDX. In addition, the favo-rable conformations of the complexes were obtained by theoretical calculations, revealing that the similar coordination type with diffe-rent bond lengths was obtained. Then, the proton affinity(PA) values of the optimized complexes were calculated to interpret the HDX observations, indicating that the higher the PA values, the more difficult it was for HDX. Overall, the experiments and theoretical calculations revealed that Pb^(2+) could induce conformational changes of LE and ME, and generate ME into a more rigid conformation than LE. The results will prompt further fundamental investigations on the conformational properties of LE/ME in coordination with Pb^(2+).
