Detection of a four-carbon sugar in interstellar space
Jiménez-Serra, I., García de la Concepción, J., Cuppen, H.M. et al. Detection of a four-carbon sugar in interstellar space. Nat Astron (2026). https://doi.org/10.1038/s41550-026-02905-7
摘要
糖类是重要的生物分子，它既作为代谢燃料、核酸骨架成分，也作为结构或能量储存聚合物。生命起源研究中的一个核心问题是：在原始地球上，单糖是如何形成的，因为在模拟前生条件的实验中，其生成浓度不足。小行星和陨石中检测到核糖、葡萄糖及其他单糖，提示它们可能具有外源起源，或许在陨石母体形成之前就已在星际介质（ISM）中生成。然而，迄今为止尚未在星际介质中观测到任何糖类。
在此，我们报告在星际介质中发现了赤藓酮糖 (erythrulose)，一种具有手性的四碳酮糖。该探测通过对银河中心分子云 G+0.693−0.027 进行超高灵敏度、宽频谱的观测实现，使用了 Yebes 40 米望远镜和 IRAM 30 米望远镜。赤藓酮糖的丰度至少是类似的三碳糖的八倍，而后者在我们超高灵敏度的观测中仍未被探测到。量子化学与天体化学模型显示，赤藓酮糖可在星际尘埃颗粒上由更简单的二碳醛类和醇类高效生成。由于酮糖在水环境中易于异构化为醛糖，星际中的赤藓酮糖可能为早期代谢与复制过程所需的糖类库提供了贡献。
Sugars are essential biomolecules, serving as metabolic fuels, nucleic acid backbone components and structural or energy-storage polymers. A central question in origin-of-life research is how monosaccharides formed on the primitive Earth, as laboratory experiments under prebiotic conditions yield insufficient concentrations. The detection of ribose, glucose and other monosaccharides in asteroids and meteorites suggests an exogenous origin, possibly in the interstellar medium (ISM) before meteoritic parent-body formation. However, no sugar has been observed in the ISM so far. Here we report the discovery of erythrulose, a chiral four-carbon ketose, in the ISM. The detection was achieved through ultrasensitive, broadband spectral surveys of the Galactic Centre molecular cloud G+0.693−0.027, using the Yebes 40 m and IRAM 30 m telescopes. Erythrulose appears to be at least eight times more abundant than analogous three-carbon sugars, which remain undetected in our ultrasensitive observations. Quantum chemical and astrochemical models indicate that erythrulose forms efficiently on interstellar dust grains from simpler two-carbon aldehydes and alcohols. As ketoses readily isomerize into aldoses in aqueous conditions, interstellar erythrulose could have contributed to the sugar inventory available for early metabolic and replication processes.