From Interstellar Sugar to the Substance of Life

An international group of scientists recently announced the discovery of glycolaldehyde outside the rotational center of the Milky Way Galaxy, about 26,000 light-years from Earth:

While others have observed glycolaldehyde in the Milky Way Galaxy,1,2 this is the first report of glycolaldehyde in a star-forming region "where planets orbiting newly formed stars are expected to exist."

Why has this discovery renewed speculation about life on other planets?  Glycolaldehyde is a simple sugar, or monosaccharide, in the most basic two-carbon form (CAS Registry Number(R) 141-46-8).  Despite its simplicity, the authors suggest that glycolaldehyde is "directly linked to the origin of life" due to its fundamental role in the synthesis of ribose (CAS Registry Number 50-69-1), a key component in the cellular macromolecule ribonucleic acid (RNA). 

The four ribose-containing nucleotide building blocks of RNA are listed below:



CAS Registry

adenylic acid (AMP)


uridylic acid (UMP)


guanylic acid (GMP)


cytidylic acid (CMP)


RNA is involved in many cellular processes, most notably the regulation of gene expression and protein synthesis.  In 1989, Sidney Altman and Thomas Cech were awarded the Nobel Prize in Chemistry for their discovery that RNA "is not only a molecule of heredity but also can function as a biocatalyst." 3  Their findings support the hypothesis that RNA, rather than DNA or protein, is the primary substance of life.  It should then come as no surprise that the discovery of interstellar glycolaldehyde has renewed speculation about life on other planets.

You can use SciFinder or STN to search the CAS databases for additional information about the research of the 2009 Nobel Laureates in Chemistry.  If your organization is enabled to use the web version of SciFinder, you can click the SciFinder links in this article to directly access details of the references.

For additional information, read the recent article in Chemical & Engineering News.

You can use SciFinder or STN to search the CAS databases for additional information about glycolaldehyde, ribose, and RNA.  Predicted and experimental properties, including proton NMR spectra, for each of these substances are included in CAS REGISTRYSM, the world's most authoritative collection of disclosed chemical substance information.  If your organization is enabled to use the web version of SciFinder, you can directly access details for the substances and references listed in this article.

Contributed by
Peter S. Carlton, Ph.D.
CAS Communications

  1. Hollis, J.M.; Lovas, F.J.; Jewell, P.R. Interstellar Glycolaldehyde: The First Sugar. Astrophys. J. 2000, 540, L107-L110.
  2. Halfen, D.T.; Apponi, A.J.; Woolf, N.; Polt, R.; Ziurys, L.M. A Systematic Study of Glycolaldehyde in Sagittarius B2(N) at 2 and 3 mm: Criteria for Detecting Large Interstellar Molecules. Astrophys. J. 2006, 639, 237-245.
  3. (accessed Dec 4, 2008).

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