Campus Units

Chemistry

Document Type

Article

Publication Version

Published Version

Publication Date

9-2008

Journal or Book Title

Journal of Chemical Theory and Computation

Volume

4

Issue

10

First Page

1788

Last Page

1794

DOI

10.1021/ct8002942

Abstract

Quantum chemistry calculations and classical molecular dynamics simulations have been used to examine the equilibria in solution between the neutral and zwitterionic forms of glycine and also of the glycyl radical. The established preference (by 30 kJ mol−1) for the zwitterion of glycine was confirmed by both the quantum chemical calculations and the classical molecular dynamics simulations. The best agreement with experiment was derived from thermodynamic integration calculations of explicitly solvated systems, which gives a free energy difference of 36.6 ± 0.6 kJ mol−1. In contrast, for the glycyl radical in solution, the neutral form is preferred, with a calculated free energy difference of 54.8 ± 0.6 kJ mol−1. A detailed analysis of the microsolvation environments of each species was carried out by evaluating radial distribution functions and hydrogen bonding patterns. This analysis provides evidence that the change in preference between glycine and glycyl radical is due to the inherent gas-phase stability of the neutral α-carbon radical rather than to any significant difference in the solvation behavior of the constituent species.

Comments

Reprinted (adapted) with permission from Journal of Chemical Theory and Computation 4 (2008): 1788, doi:10.1021/ct8002942. Copyright 2008 American Chemical Society.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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Included in

Chemistry Commons

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