An amino acid essential for human growth detected in star-forming region

Tryptophan is one of the 20 necessary amino acids for human development. 
Mrigakshi Dixit
Representational image of star forming region.
Representational image of star forming region.


As they say, we are all made of stardust! Interestingly, an amino acid essential for normal human growth has been spotted in the interstellar space. 

The amino acid tryptophan has been discovered in the star-forming region IC 348, which is located in the constellation Perseus around 1,000 light-years from Earth. Tryptophan is one of the 20 necessary amino acids for human development. 

Susana Iglesias-Groth of The Instituto de Astrofisica de Canarias (IAC) led the new research. 

Detection of the amino acid

The now-retired Spitzer space telescope gathered evidence of this amino acid in the interstellar medium. 

This star-forming region's Perseus Molecular Complex contained a high concentration of tryptophan. 

The area is generally undetectable to the naked eye, but tryptophan molecules sparkle brilliantly when viewed through infrared wavelengths. The amino acid also has a distinct infrared light signature, making it an excellent target for our infrared-based telescope.

An amino acid essential for human growth detected in star-forming region
Artistic composition of tryptophan molecules in the star-forming region IC 348 located in the constellation Perseus.

The telescope's spectroscopic data of infrared light found 20 emission lines of the tryptophan. The temperature of the gas in which the amino acid occurs was also measured, and it was found to be roughly 280 Kelvin, or 7 degrees Celsius.

“The novelty of this work is that tryptophan has never before been detected in the interstellar medium, and furthermore, in spite of decades of research, there has been no confirmed detection of other amino acids in any other star formation region,” said Iglesias-Groth, in an official release.

According to the author, IC 348 is an "extraordinary chemical laboratory" that enables the most sensitive searches for various molecules in the interstellar medium.

Previously, Iglesias-Groth discovered the existence of water and hydrogen molecules in IC 348 at the same temperatures. Other compounds found by the author from this unusual star formation zone include carbon dioxide, hydrogen cyanide, acetylene, and benzene. 

Tryptophan may also be present in other star-forming regions 

The findings suggest that tryptophan may be naturally present in other star-forming areas. And amino acids are quite likely to be enriching the gas in the star-forming area and contributing to the early chemistry of planetary systems.

Amino acids of various sorts have been discovered in meteorites and may have existed as early as the birth of the Solar System.

Iglesias-Groth concluded: "The evidence for tryptophan in the Perseus molecular complex should encourage additional effort to identify other amino acids in this region and in other star-forming regions. It is a very exciting possibility that the building blocks of proteins are widely present in the gas from which stars and planets form - it may be key for the development of life in exoplanetary systems”.

The research is published in Monthly Notices of the Royal Astronomical Society.

Study abstract:

We have used spectra of the Spitzer Space Telescope to conduct a search for the aromatic amino acid tryptophan in the interstellar gas of the young star cluster IC 348. For all the strongest mid-infrared (mid-IR) laboratory bands of tryptophan, we have found counterpart emission lines in the observed spectrum which are consistent in wavelength and strength with the laboratory measurements. Assuming that the detected emission lines are due to tryptophan and using the measured fluxes, we estimate a tryptophan column density in the line of sight of the core of IC 348 in the range 109–1011 cm−2. The observed emission lines are also found in the combined spectrum of >30 interstellar locations obtained in diverse unrelated star-forming regions observed by Spitzer. This could be an indication that the molecule causing the emission is widespread in interstellar space. Future high spectral resolution mid-IR searches for proteinogenic amino acids in protostars, protoplanetary discs, and in the interstellar medium will be key to study an exogenous origin of meteoritic amino acids and to understand how the pre-biotic conditions for life were set in the early Earth.

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