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 language | English (US) |
|---|---|
| Pages (from-to) | 1103-1110 |
| Number of pages | 8 |
| Journal | Journal of Mass Spectrometry |
| Volume | 30 |
| Issue number | 8 |
| DOIs | |
| State | Published - 1995 |
Fingerprint
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 journal › Article
}
TY - JOUR
T1 - H-D exchange kinetics of alcohols and protonated peptides
T2 - Effects of structure and proton affinity
AU - Green, M. K.
AU - Gard, E.
AU - Bregar, J.
AU - Lebrilla, Carlito B
PY - 1995
Y1 - 1995
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0029162770&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029162770&partnerID=8YFLogxK
U2 - 10.1002/jms.1190300807
DO - 10.1002/jms.1190300807
M3 - Article
AN - SCOPUS:0029162770
VL - 30
SP - 1103
EP - 1110
JO - Biomedical Mass Spectrometry
JF - Biomedical Mass Spectrometry
SN - 1076-5174
IS - 8
ER -