Charge loss in gas-phase multiply negatively charged oligonucleotides

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Biophysics

Background:

• Gaseous negatively charged oligonucleotides exhibit exceptionally slow electron charge loss.
• Understanding this charge loss mechanism is crucial for mass spectrometry and ion manipulation.

Purpose of the Study:

• To elucidate the mechanism of slow electron detachment from gaseous oligonucleotide anions.
• To determine the rate-limiting step in the charge loss process of T(5)(3-) anions.

Main Methods:

• Molecular dynamics simulations were performed on a T(5)(3-) oligonucleotide anion.
• Simulations investigated electron detachment via internal Coulomb repulsion.
• Special techniques were used to extrapolate results for slow processes.

Main Results:

• Electron binding strength at phosphate sites is reduced by Coulomb repulsion.
• Geometrical fluctuations of phosphate sites modulate Coulomb repulsion energies.
• Autodetachment occurs when Coulomb potential exceeds the electron binding strength.
• The rate of geometrical fluctuations, not electron tunneling, limits the electron loss rate.

Conclusions:

• The slow charge loss of gaseous oligonucleotide anions is governed by Coulomb repulsion dynamics.
• Geometrical fluctuations are the key factor determining electron detachment rates.
• This study provides insights into ion stability and behavior in the gas phase.