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L-Cysteine

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Gas phase ion energetics data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess

Quantity Value Units Method Reference Comment
Proton affinity (review)903.2kJ/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity869.3kJ/molN/AHunter and Lias, 1998HL

De-protonation reactions

C3H6NO2S- + Hydrogen cation = L-Cysteine

By formula: C3H6NO2S- + H+ = C3H7NO2S

Quantity Value Units Method Reference Comment
Deltar1395. ± 9.2kJ/molCIDCJones, Bernier, et al., 2007gas phase; B
Deltar1399. ± 9.6kJ/molG+TSTian, Pawlow, et al., 2007gas phase; Calcn say SH is 3.1 kcal/mol more acidic than CO2H. See DeBlase, Kass, et al., 2014 for spectroscopy saying that it is a cyclic H-bonded species; B
Quantity Value Units Method Reference Comment
Deltar1370. ± 8.8kJ/molN/ATian, Pawlow, et al., 2007gas phase; Calcn say SH is 3.1 kcal/mol more acidic than CO2H. See DeBlase, Kass, et al., 2014 for spectroscopy saying that it is a cyclic H-bonded species; B
Deltar1364. ± 13.kJ/molCIDCO'Hair, Bowie, et al., 1992gas phase; B

References

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Jones, Bernier, et al., 2007
Jones, C.M.; Bernier, M.; Carson, E.; Colyer, K.E.; Metz, R.; Pawlow, A.; Wischow, E.D.; Webb, I.; Andriole, E.J.; Poutsma, J.C., Gas-phase Acities of the 20 Protein Amino Acids, Int. J. Mass Spectrom., 2007, 267, 1-3, 54-62, https://doi.org/10.1016/j.ijms.2007.02.018 . [all data]

Tian, Pawlow, et al., 2007
Tian, Z.X.; Pawlow, A.; Poutsma, J.C.; Kass, S.R., Are carboxyl groups the most acidic sites in amino acids? Gas-phase acidity, H/D exchange experiments, and computations on cysteine and its conjugate base, J. Am. Chem. Soc., 2007, 129, 17, 5403-5407, https://doi.org/10.1021/ja0666194 . [all data]

DeBlase, Kass, et al., 2014
DeBlase, A.F.; Kass, S.R.; Johnson, M.A., On the character of the cyclic ionic H-bond in cryogenically cooled deprotonated cysteine, Phys. Chem. Chem. Phys., 2014, 16, 10, 4569-4575, https://doi.org/10.1039/c3cp54117g . [all data]

O'Hair, Bowie, et al., 1992
O'Hair, R.J.; Bowie, J.H.; Gronert, S., Gas Phase Acidity of the alpha-Amino Acids, Int. J. Mass Spectrom. Ion Proc., 1992, 117, 23, https://doi.org/10.1016/0168-1176(92)80083-D . [all data]


Notes

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