Naslov
The Nature of Glycine and its alpha-Carbon Radical in Aqueous Solution: A Theoretical Investigation

Autori
Wood, Geoffrey P. F. ; Gordon, Mark S. ; Radom, Leo ; Smith, David M.

Izvornik
Journal of chemical theory and computation (1549-9618) 4 (2008), 10; 1788-1794

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Quantum chemistry ; molecular dynamics ; glycine ; glycyl radical ; solvation

Sažetak
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 alpha-carbon radical rather than to any significant difference in the solvation behavior of the constituent species.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija, Biologija

POVEZANOST RADA