The B1-fragment Ion from Protonated Glycine is an Electrostatically-bound Ion/Molecule Complex of CH 2=NH+2 and CO
✍ Scribed by W. D. van Dongen; W. Heerma; J. Haverkamp; C. G. de Koster
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 285 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0951-4198
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✦ Synopsis
The stability of the B,-ion from glycylglycine dipeptides was studied using collision-induced dissociation experiments and ab initi0 calculations. This study reveals that the B,-type ion from glycine should be considered as an electrostatically bound iodmoecule complex, which dissociates into a glycine immonium ion (A,) and a carbon monoxide molecule. The stability of this complex has been calculated at various levels of the theory. At the highest level of theory (#RHF/6-311G**) it is found that the energy requirement, including zero-point vibrational energy correction, for dissociation into a glycine immonium A, ion and a neutral carbon monoxide CO molecule is -4.0 kJ mol-'. Furthermore it could be concluded that B,-ions from glycine are stable if they are present as N-acylated species. The formation of stable B ions requires at least two carbonyl groups in the peptide backbone moiety.