Thermochemistry of Multiply Charged Melittin in the Gas Phase Determined by the Modified Kinetic Method
✍ Scribed by Igor A. Kaltashov; Catherine Fenselau
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 444 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0951-4198
No coin nor oath required. For personal study only.
✦ Synopsis
The modified kinetic method was expanded to measuring gas-phase basicities of biopolymers carrying two or more charges. Relative rates of the unimolecular dissociation of metastable multiply charged proton-bound dimers formed by melittin and reference bases provided the values of 'apparent' gas-phase basicities. These numbers are offset by the height of the reverse activation energy barrier due to Coulombic repulsion in charge separation processes, which have been measured experimentally using mass-analyzed ion kinetic energy spectrometry. The gas-phase basicity of doubly prutonated melittin was determined to be 200.0 23.4 kcal/mol, while the basicity of the same polypeptide carrying three protons was determined to be 179.1 23.6 kcal/mol.