H-D exchange kinetics of alcohols and protonated peptides: Effects of structure and proton affinity

M. K. Green, E. Gard, J. Bregar, Carlito B Lebrilla

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The kinetics of gas-phase H-D exchange reactions of a series of protonated amino acids and peptides with deuterium-substituted alcohols (D2O, CH3OD, C2H5OD and 1-C4H9OD) were studied in an external source Fourier transform mass spectrometer. The number of exchanges observed on the time-scale of these experiments ranged from one to the total number of 'labile' substrate hydrogens, depending on the amino acid and the deuterating reagent. Exchange efficiencies, k/k(ADO), varied from <0.001 to 0.3. Within the series ROD, the reactivity increased with increasing size of the R group. For the amino acids with alkyl side-chains, a roughly linear correlation of log(k/k(ADO)) with proton affinity difference (ΔPA = PA of unprotonated substrate - PA of reagent) was observed. The amino acids lysine and histidine and the dipeptides alanylglycine and diglycine showed higher reactivity and greater tendency for multiple exchange, with a weaker dependence on ΔPA. The ability of a peptide and an alcohol to exchange efficiently even when ΔPA is larger is attributed to the occurrence of exchange within a cyclic hydrogen-bonded complex, in which the deuterating agent forms a bridge between the site of protonation and a basic site on the substrate.

Original languageEnglish (US)
Pages (from-to)1103-1110
Number of pages8
JournalJournal of Mass Spectrometry
Volume30
Issue number8
DOIs
StatePublished - 1995

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Peptides
peptides
amino acids
affinity
Protons
Amino acids
alcohols
Alcohols
Amino Acids
Kinetics
protons
kinetics
Hydrogen
reagents
alanylglycine
Substrates
reactivity
Glycylglycine
histidine
Dipeptides

ASJC Scopus subject areas

  • Organic Chemistry
  • Spectroscopy
  • Biophysics

Cite this

H-D exchange kinetics of alcohols and protonated peptides : Effects of structure and proton affinity. / Green, M. K.; Gard, E.; Bregar, J.; Lebrilla, Carlito B.

In: Journal of Mass Spectrometry, Vol. 30, No. 8, 1995, p. 1103-1110.

Research output: Contribution to journalArticle

Green, M. K. ; Gard, E. ; Bregar, J. ; Lebrilla, Carlito B. / H-D exchange kinetics of alcohols and protonated peptides : Effects of structure and proton affinity. In: Journal of Mass Spectrometry. 1995 ; Vol. 30, No. 8. pp. 1103-1110.
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