An international team of scientists led by CAB researcher Izaskun Jiménez-Serra has identified sugar in interstellar space for the first time — erythrulose. This discovery is significant because sugars are key biomolecules in living organisms: they form the basis of DNA and RNA and play an important role in metabolic processes.
In theories regarding the origin of life, sugars are also essential for the synthesis of the first nucleic acids. Previously, sugars such as ribose and glucose had only been found in meteorite and asteroid samples, suggesting their possible origin from the primordial molecular cloud from which the solar system formed. However, until now, no sugar had been directly detected in the interstellar medium.
Erythrulose is the only known four-carbon ketose. On Earth, it is typically found in raspberries and is used in self-tanning products. It was detected in the molecular cloud G+0.693−0.027, located near the center of our galaxy, the Milky Way.
The discovery was made possible by highly sensitive broadband spectroscopic studies conducted using the 40-meter Yebes radio telescope and the 30-meter telescope of the Institute of Radio Astronomy in the millimeter range (IRAM). The results are published in the journal Nature Astronomy.
Unexpected chemical pathway of formation
The team identified 12 spectral lines corresponding to the laboratory spectrum of erythrulose, measured at the University of the Basque Country. The study also showed that this sugar is at least eight times more abundant than similar three-carbon sugars, none of which have been detected in the same region.
“This discovery was unexpected, as the prevailing view in astrochemistry is that interstellar molecules are formed by the sequential addition of carbon atoms,” said Izaskun Jiménez-Serra, lead author of the study. Collaborating with chemists from the University of Extremadura and Radboud University (Netherlands), the CAB team established that erythrulose can form in interstellar ices from simpler two-carbon alcohols and aldehydes.
Possible delivery to Earth
Based on the measured amount of erythrulose in the molecular cloud G+0.693−0.027, researchers estimate that between 0.5 and 50 million tons of this sugar could have reached the Earth’s surface during the Late Heavy Bombardment, which occurred approximately 4.1–3.8 billion years ago.
The presence of erythrulose in interstellar space suggests the existence of an alternative source of sugars that could have contributed to the emergence of the first metabolic processes and replication mechanisms on early Earth. “The detection of erythrulose is very exciting because it opens the possibility of detecting other sugars in space, such as ribose, which is part of RNA, and other important molecules for the origin of life,” said Carlos Briones, co-author of the study.
Source: Phys.org
