The conformational space of beta-turns of Ala-Gly dipeptide is analyzed theoretically using quantum mechanical methods. A number of potential minima are obtained and characterized. The potential energy surface suggests that beta-turn conformers are susceptible to rapid radical formation, which leads to potential L and D epimerization. The calculated thermodynamics show that the radical mediated epimerization is possible and that the estimated barrier height for hydrogen abstraction on the C alpha is the lowest for the Gly residue. (C) 2017 Elsevier B.V. All rights reserved.