The conformational space of β-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 β-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 Cα is the lowest for the Gly residue.

中文翻译：

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Ala-Gly二肽与β-turn二级结构的反应性

理论上使用量子力学方法分析了Ala-Gly二肽β-转角的构象空间。获得并表征了许多潜在的最小值。势能表面表明β-转角构象异构体易于快速形成自由基，从而导致潜在的L和D差向异构化。计算的热力学表明，自由基介导的差向异构化是可能的，并且对于Cly残基，Cα上夺氢的估计势垒高度最低。