A comparison of the gas phase acidities of phospholipid headgroups: Experimental and computational studies

Thomas, M. C., Mitchell, T. W., & Blanksby, S. J. (2005) A comparison of the gas phase acidities of phospholipid headgroups: Experimental and computational studies. Journal of the American Society for Mass Spectrometry, 16(6), pp. 926-939.

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Proton-bound dimers consisting of two glycerophospholipids with different headgroups were prepared using negative ion electrospray ionization and dissociated in a triple quadrupole mass spectrometer. Analysis of the tandem mass spectra of the dimers using the kinetic method provides, for the first time, an order of acidity for the phospholipid classes in the gas phase of PE < PA << PG < PS < PI. Hybrid density functional calculations on model phospholipids were used to predict the absolute deprotonation enthalpies of the phospholipid classes from isodesmic proton transfer reactions with phosphoric acid. The computational data largely support the experimental acidity trend, with the exception of the relative acidity ranking of the two most acidic phospholipid species. Possible causes of the discrepancy between experiment and theory are discussed and the experimental trend is recommended. The sequence of gas phase acidities for the phospholipid headgroups is found to (1) have little correlation with the relative ionization efficiencies of the phospholipid classes observed in the negative ion electrospray process, and (2) correlate well with fragmentation trends observed upon collisional activation of phospholipid [M - H](-) anions. (c) 2005 American Society for Mass Spectrometry.

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ID Code: 68947
Item Type: Journal Article
Refereed: Yes
Keywords: driven fragmentation processes, energy collisional activation, tandem, mass-spectrometry, extended kinetic method, electrospray-ionization, mechanistic proposal, entropy, density, rafts
DOI: 10.1016/j.jasms.2005.02.019
ISSN: 1044-0305
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000)
Divisions: Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Springer
Deposited On: 24 Mar 2014 04:53
Last Modified: 20 Jan 2016 21:30

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