by Michelle Starr
A meteor during the peak of
the 2009 Leonid Meteor Shower.
(Navicore/Wikimedia Commons/CC BY 3.0)
A new discovery could be a clue for us to see if life could emerge
elsewhere in the Solar System.
Using a new analysis
technique, scientists think they have found an extraterrestrial
protein, tucked inside a meteorite that fell to Earth 30 years ago.
If their results can be replicated, it will be the first protein
ever identified that didn't originate here on Earth.
"This paper (Hemolithin
- A Meteoritic Protein containing Iron and Lithium)
characterizes the first protein to be discovered in a
meteorite," the researchers wrote in a paper uploaded to
preprint server arXiv.
Their work is yet to be
peer reviewed, but the implications of this finding are noteworthy.
Over the last few years, meteorites from the wider Solar System have
been yielding some building blocks for life as we know it. Cyanide,
which could play a role in building molecules necessary for life;
ribose, a type of sugar that is found in RNA; and amino acids,
organic compounds that combine to form proteins.
Researchers have now revisited the meteorites that yielded the
latter. Led by physicist Malcolm McGeoch of superconductor
X-ray source supplier PLEX Corporation, the team focused their
search for something more.
Using "state-of-the-art" mass spectrometry, they found what they
believe to be protein in a meteorite called
Acfer 086, found in Algeria in
While not proof of extraterrestrial living creatures, this protein
discovery makes for yet another of life's building blocks to be
found in a space rock.
There are many processes
that can produce protein, but life, as far as we know, can't exist
"In general, they're
taking a meteor that has been preserved by a museum and has been
And they are
modifying the techniques that they're using in order to be able
to detect amino acid inside of this meteor, but in a higher
signal ratio," astronomer and chemist Chenoa Tremblay of CSIRO
Astronomy & Space Science in Australia, who was not involved in
the research, told ScienceAlert.
Not only did the team
find the glycine amino acid with a stronger signal than previous
they found that it
was bound with other elements, such as iron and lithium.
When they performed
modeling to see what was occurring, they found that the glycine
wasn't isolated; it was part of a protein.
The researchers are calling this newly discovered protein
While hemolithin is
structurally similar to terrestrial proteins, its ratio of deuterium
to hydrogen was not matched by anything on Earth. It is, however,
consistent with long-period comets.
This suggests, the researchers argue, that the structure they have
identified as protein is of extraterrestrial origin, and possibly
formed in the proto-solar disc, over 4.6 billion years ago.
But, they also note that there's a possibility what they found might
not be protein. Although the team thinks it's the most likely
explanation, it's also possible that their finding is actually a
polymer - a broad class of molecules, of which proteins are only
So it's a little too early to get too carried away.
But, overall, Chenoa
Tremblay is impressed with the work.
"I think this is
really exciting," she said.
"I think that it's
got a lot of really interesting implications and a lot of
compelling arguments. And I think it's a really great step
There are several next
steps that the research could take.
Other scientists can take
the spectra, and use modeling software to try to replicate
structures that produce the same or similar spectra. That could help
determine whether we're looking at protein or a different kind of
Similar techniques could now be used on other meteorites in which
amino acids have been found, to see if similar structures can be
As Tremblay explains, recent studies on the International Space
Station have indicated ,
be easier to make in space because of the reduced gravity",
scientists have actually managed to produce quite large protein
molecules, stable enough to bring down to Earth.
"So we're pretty sure
that proteins are likely to exist in space," she says.
"But if we can
actually start finding evidence of their existence, and what
some of the structures and the common structures might be, I
think that's really interesting and exciting."
The research (Hemolithin
- A Meteoritic Protein containing Iron and Lithium) is currently
available on arXiv.