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The search for sugars in interstellar space is hampered by a lack of spectroscopic information. D-Ribose is now the first C5 sugar observed in the gas phase using microwave spectroscopy. The rotational spectrum revealed six conformations of free ribose, adopting preferentially ß-pyranose rings and higher-energy α-pyranose forms. No evidence of α-/β-furanoses or linear forms was found, unlike biological systems, where β-furanoses are found in RNA.
[Credit: Angewandte Chemie, DOI 10.1002/anie.201107973] |
There are numerous research teams to be first in the race to detect this sugar in gas phase, using high-resolution techniques. Problems have arisen in trying to vaporise it due to the thermal instabilities caused by loss of water. "Only if you avoid the processes of decomposition on dehydration and manage to isolate the sugar, thus obviating the changes produced by neighbouring molecules, will you be in a position to characterise its structure", explained Mr Emilio José Cocinero, researcher at the Department of Physical Chemistry of the University of the Basque Country (UPV-EHU). His latest research has become amongst the first worldwide to have managed to observe a sugar – a ribose – in the gas phase and to characterise a number of its structures. His article, "Ribose Found in the Gas Phase", published by the Angewandte Chemie International Edition, was announced on the front cover of the April issue of the scientific journal and also highlighted in the on-line version. This publication has an impact factor of 12.730, making it the most important in the field of Chemistry.
Participating in the research, led by Mr Cocinero, was Ms Patricia Écija, Mr Francisco José Basterretxea, Mr José Andrés Fernández and Mr Fernando Castaño, from the UPV/EHU, with the collaboration of Mr Alberto Lesarri from the University of Valladolid and of Jens-Uwe Grabow, from the University of Hannover (Germany), being undertaken in its totality with the team formed at the Basque university.
In concrete, in order to observe the ribose in gas phase, microwave spectroscopy was used combined with ultra-rapid laser vaporisation with ultraviolet light. Not only was it isolated and observed, but six different structures of the ribose were detected. "Sugars are super flexible molecules that can take on many different configurations. We have managed to detect the six most stable structures of the free ribose", explained the lead researcher. However, all the structures detected show rings of six members, i.e. the structures involved are very different from those shown in RNA or ADNA ribose or its derivatives, where the rings are five-membered. "Given that the genetic material has a different configuration, it is unlikely that the first living beings had ribose. Thermal instability and the preference for 6-member rings would appear to exclude the possibility that the first genetic material was made up of this sugar", concluded Mr Cocinero. With this door opened to the study of sugars in gas phase, it will be "easier" to obtain information on the role of sugars in the origin of the first living beings.