Observation of cysteine thiolate and-S⋯H-O intermolecular hydrogen bond

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Pages (from-to)12603-12606
Journal / PublicationJournal of Physical Chemistry A
Volume110
Issue number46
Publication statusPublished - 23 Nov 2006
Externally publishedYes

Abstract

The cysteine anion was produced in the gas phase by electrospray ionization and investigated by photoelectron spectroscopy at low temperature (70 K). The cysteine anion was found to exhibit the thiolate form [-SCH 2CH(NH2)CO2H], rather than the expected carboxylate form [HSCH2CH(NH2)CO2-]. This observation was confirmed by two control experiments, that is, methyl cysteine [CH3SCH2CH(NH2)CO2 -] and cysteine methyl ester [-SCH2CH(NH 2)CO2CH3]. The electron binding energy of [-SCH2CH(NH2)CO2H] was measured to be about 0.7 eV blue-shifted relative to [-SCH2CH(NH 2)CO2CH3] due to the formation of an intramolecular -S-⋯HO2C- hydrogen bond in the cysteine thiolate. Theoretical calculations at the CCSD(T)/6-311++G-(2df,p) and B3LYP/6-311++G(2df,p) levels were carried out to estimate the strength of this intramolecular -S-⋯HO2C- hydrogen bond. Combining experimental measurements and theoretical calculations yielded an estimated value of 16.4 ± 2.0 kcal/mol for the -S-⋯HO 2C- intramolecular hydrogen-bond strength. © 2006 American Chemical Society.

Citation Format(s)

Observation of cysteine thiolate and-S⋯H-O intermolecular hydrogen bond. / Woo, Hin-Koon; Lau, Kai-Chung; Wang, Xue-Bin et al.

In: Journal of Physical Chemistry A, Vol. 110, No. 46, 23.11.2006, p. 12603-12606.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review