Year: 2025
Type: article
Abstract: The intrinsic contradiction between homochirality and the phenomenon of racemization poses both challenges and opportunities for the exploration of life’s origin, urgently necessitating a deep understanding of the racemization mechanism of essential small life molecules, particularly amino acids. Herein, we demonstrate that the racemization of amino acid molecules in aqueous environments can occur by a dual-path coexistence (DPC) mechanism via the carboxyl (COOH) and amino (NH 2 ) groups simultaneously, which provides a new interpretation of previous experimental results obtained in neutral to weakly acidic environments. Results show that the quantum mechanical tunneling (QMT) effect plays the pivotal role in this DPC mechanism, as evidenced by the tunneling hindrance of the NH 2 reaction and the tunneling enhancement of the COOH reaction. Further, the disparity in the QMT effect contributes to a crossover between COOH and NH 2 reactions at ∼250 K, such that NH 2 reactions dominate at high temperatures (>300 K), whereas COOH reactions dominate at low temperatures (<200 K). This study proposes a DPC mechanism for amino acid racemization, mediated by the QMT effect, that fills a gap in the understanding of amino acid racemization mechanisms and offers valuable insights into the origin of homochirality in the extreme environments of the early Earth.
Authors: Xinrui Yang, Rui Liu, Ruiqi Xu, Zhaohua Cui, Wei Feng, Sean Xiao-An Zhang, Zhigang Wang
Institutions: Jilin University, Institute for Atomic and Molecular Physics
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: 超原子间的相互作用理论研究, G3104115121, G3110299068
OpenAlex ID: W4414993962