Investigation of protonated and sodiated leucine-enkephalin by hydrogen–deuterium exchange and theoretical calculations. Issue 13 (11th June 2015)

• Record Type: Journal Article
• Authors: Chen, Yinjuan; Yue, Lei; Li, Zhenhua; Ding, Xunlei; Wang, Liang; Dai, Xinhua; Fang, Xiang; Pan, Yuanjiang; Ding, Chuan-Fan
• Is Part Of: Analytical methods. Volume 7:Issue 13(2015)
• Page Start: 5551
• Page End: 5556
• Publication Date: 2015-06-11
• Subjects: Chemistry, Analytic -- Periodicals; Analytical biochemistry -- Periodicals; Chemical laboratories -- Standards -- Periodicals; 543.1905
• DOI: 10.1039/c5ay00684h
• Languages: English
• ISSNs: 1759-9660

Abstract

Abstract : Comparison of protonated and sodiated leucine-enkephalin by hydrogen–deuterium exchange mass spectrometry and theoretical calculations. Abstract : In this work, protonated and sodiated leucine-enkephalin (LE) were investigated by gas-phase hydrogen–deuterium exchange (HDX) performed on a linear ion trap time-of-flight mass spectrometer. It is found that more hydrogen atoms are exchanged in protonated LE than in sodiated LE, indicating the different conformations of the two peptide ions. To clarify further the experimental results, the conformations were calculated by using density functional theory, which shows that the terminal amino group is the most thermodynamically stable protonation site, while the sodium ion coordinated to four carbonyl oxygen atoms forms the most favourable sodium adduct. Limited HDX reactions of sodiated LE are explained by the rigid conformation and fewer exchangeable acidic hydrogen atoms from sodium coordination.