Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Barrio Sarriena, S/N, Leioa, 48940, Spain.
Instituto Biofisika (UPV/EHU-CSIC), University of the Basque Country (UPV/EHU), Barrio Sarriena S/N, Leioa, 48940, Spain.
Chemistry. 2022 Jan 3;28(1):e202103636. doi: 10.1002/chem.202103636. Epub 2021 Dec 2.
One of the most fascinating questions in chemistry is why nature chose CGAT as the alphabet of life. Very likely, such selection was the result of multiple factors and a long period of refinement. Here, we explore how the intermolecular interactions influenced such process, by characterizing the formation of dimers between adenine, theobromine and 4-aminopyrimidine. Using a combination of mass-resolved excitation spectroscopy and DFT calculations, we determined the structure of adenine-theobromine and 4-aminopyrimidine-theobromine dimers. The binding energy of these dimers is very close to the canonical adenine-thymine nucleobases. Likewise, the dimers are able to adopt Watson-Crick conformations. These findings seem to indicate that there were many options available to build the first versions of the informational polymers, which also had to compete with other molecules, such as 4-aminopyrimidine, which does not have a valid attaching point for a saccharide. For some reason, nature did not select the most strongly-bonded partners or if it did, such proto-bases were later replaced by the nowadays canonical CGAT.
化学中最引人入胜的问题之一是，大自然为何选择 CGAT 作为生命的字母表。很可能，这种选择是多种因素和长期精炼的结果。在这里，我们通过研究腺嘌呤、可可碱和 4-氨基嘧啶之间二聚体的形成，探讨了分子间相互作用如何影响这一过程。我们结合质谱分辨激发光谱和 DFT 计算，确定了腺嘌呤-可可碱和 4-氨基嘧啶-可可碱二聚体的结构。这些二聚体的结合能非常接近规范的腺嘌呤-胸腺嘧啶核苷酸碱基。同样，二聚体能够采用 Watson-Crick 构象。这些发现似乎表明，有许多选择可以构建信息聚合物的最初版本，这些聚合物也必须与其他分子竞争，例如 4-氨基嘧啶，它没有用于连接糖的有效附着点。由于某种原因，大自然没有选择结合最强的伙伴，如果它选择了，那么这些原始碱基后来就被现在的规范 CGAT 取代了。
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