The first known extraterrestrial protein has been found inside a meteorite — named Acfer 086 — that fell to Earth in Algeria 30 years ago, a study has found.
The protein — hemolithin — contains iron and lithium, suggesting that the building blocks of life could already exist out in space.
Meteorites containing hemolithin could therefore play a role in seeding life on habitable planets like the Earth by delivering proteins to their surfaces.
Hemolithin is a relatively small protein, composed mainly of the amino acid glycine with caps of iron, lithium and oxygen at its ends.
While all of these elements are familiar to scientists, this is the first time that such a configuration has been seen on the Earth.
Although the molecule's presence isn't necessarily indicative of life, it could have played a role in starting creating such — with the iron oxide tips at the ends of the hemolithin molecules known to use light to split water into hydrogen and oxygen.
'It is a good candidate molecule to split water,' paper author Julie McGeoch of the PLEX Corporation, a superconductor X-ray source supplier, told New Atlas.
This, she added, means it could 'represent a first energy source to chemistry, going on to biochemistry on the surface of planets like Earth in terms of their mass and distance from their sun.'
'This could apply to planets throughout the Universe.'
Although hemolithin is structurally similar to the proteins with which we are familiar, the protein's ratio of hydrogen to isotope deuterium did not match anything found on Earth.
However, the ratio did bear a similarity to the composition of comets from the Oort cloud, the sphere of icy planetesimals that surrounds the solar system.
According to the researchers,, this suggests that the hemolithin in Acfer 086 may have formed in the proto-solar disk, some 4.6 billion years ago.
It is not entirely clear how a complex protein like hemolithin might have formed in the Acfer 086 meteorite, although finding simple amino acids and their precursors — like sugars and organic materials — in space is not unprecedented.
Individual molecules of glycine, however, have been predicted to form on the surface of dust grains — which could potentially have linked up to eventually form proteins if exposed to the right conditions in warm molecular clouds.
A pre-print of the researchers' article, which has not yet been peer-reviewed, can be read on the arXiv repository.
This article has been adapted from its original source.
