With outer space being speculated as the source of handedness in molecules of biological importance, there is a great need to explore the gas-phase stereoinversion in molecules under the conditions akin to interstellar medium. In this work, quantum-mechanical computations are performed to trace the pathways for gas-phase stereoinversion in isoleucine, an amino acid with two chiral centres. Contrary to the previous such work on a two-chiral centre proteinogenic amino acid, threonine, the present work could not trace a complete stereoinversion pathway on the potential energy surface of isoleucine. The failure in case of isoleucine is attributed to its branched aliphatic side chain which hindered a complete inversion in isoleucine. However, the diastereomeric conversion pathways explored in this work for isoleucine support the distribution of different stereoisomers reported in the meteoritic composition. Notably, this study also revealed that the chirality of the aldehydic precursors may hold the key to enantio-biasing observed for isoleucine in the meteoritic samples.

随着外层空间被认为是具有生物学重要性的分子的惯用性来源，迫切需要探索类似于星际介质的条件下分子中的气相立体转化。在这项工作中，进行量子力学计算以追踪异亮氨酸（一种具有两个手性中心的氨基酸）中气相立体转化的途径。与先前关于双手性中心蛋白氨基酸苏氨酸的此类研究相反，本研究无法在异亮氨酸的势能面上追踪到完整的立体转化途径。在异亮氨酸的情况下的失败归因于其支链的脂族侧链，其阻碍了异亮氨酸的完全转化。然而，在这项工作中探索的异亮氨酸的非对映异构转化途径支持了在气象组成中报道的不同立体异构体的分布。值得注意的是，这项研究还表明，醛前体的手性可能是在陨石样品中观察到的异亮氨酸对映体偏性的关键。