This article needs attention from an expert in Chemicals.March 2020)(
|(iron and lithium-containing protein,|
|Function||unknown, although possibly able to split water to hydroxyl and hydrogen molecules|
Hemolithin is an iron and lithium-containing protein, purported to be found inside a meteorite called Acfer 086, a CV3 carbonaceous chondrite Allende meteorite, and thought to be the first protein discovered that may be of extraterrestrial origin. The protein was detected by teams of scientists, led by biochemist Julie McGeoch, from Harvard University, and from the biotech and physics companies of Bruker Scientific and the superconductor X-ray source supplier PLEX Corporation. The study is an extension of published and unpublished results by the teams.
The detected hemolithin protein was reported to have been found inside a meteorite called Acfer 086, a CV3 carbonaceous chondrite Allende meteorite, which was discovered in Agemour, Algeria in 1990.
Hemolithin, the newly found protein, was found, aided by the use of "state-of-the-art" mass spectrometry, to be largely composed of glycine, hydroxyglycine and amino acids. Hemolithin also contained atoms of oxygen, lithium and iron in an up-to-now unobserved arrangement. The researchers noted that the protein was related to “very high extraterrestrial" ratios of Deuterium/Hydrogen (D/H); such high D/H ratios are not found anywhere on Earth, but are "consistent with long-period comets" and suggest, as reported, "that the protein was formed in the proto-solar disc or perhaps even earlier, in interstellar molecular clouds that existed long before the Sun’s birth".
A natural development of hemolithin may have started with glycine forming first, and then later linking with other glycine molecules into polymer chains, and later still, combining with iron and oxygen atoms. The iron and oxygen atoms reside at the end of the newly found molecule. The researchers speculate that the iron oxide grouping formed at the end of the molecule may be able to absorb photons, thereby enabling the molecule to split water (H2O) into hydrogen and oxygen and, as a result, produce a source of energy that might be useful to the development of life.
Nonetheless, exobiologist and chemist Jeffrey Bada expressed concerns about the possible protein discovery commenting, "The main problem is the occurrence of hydroxyglycine, which, to my knowledge, has never before been reported in meteorites or in prebiotic experiments. Nor is it found in any proteins. ... Thus, this amino acid is a strange one to find in a meteorite, and I am highly suspicious of the results." Although some scientists seem supportive of the study, other scientists may be less so. [Note: Research Author Reply]: "On the question of hydroxy glycine in hemolithin, there is presented in the Hemolithin MS very clear evidence of multiple oxidations of a 17 glycine polymer: The hemolithin MS (arXiv) shows in figure S3.3 a characteristic oxidation series in which 2, 3, 4, 5, and 6 oxygen atoms bond to glycine residues within a 17 glycine chain. This converts the corresponding numbers of mass 57 glycine residues into mass 73 hydroxy glycine residues (MS pages 27 and 28)."
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The possible finding of the hemolithin protein supports the notion that life on Earth may not have started on Earth after all, but may have come from outer space instead – a process known as panspermia.
Besides this possible discovery of an extraterrestrial protein, other evidences of complex chemistry (amino acids, polycyclic aromatic hydrocarbons, sugars, ribose, tholins) occurring in outer space have been accumulating from recent astrobiology studies, including those related to meteorites and comets. The presence of such complex chemistry occurring in the cosmos, as well as the observation by biologist Stephen Blair Hedges that life may have arisen quickly on the very early Earth, suggests that life may be widespread thoughout the universe.
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- McGeoch, Malcolm. W.; Dikler, Sergei; McGeoch, Julie E. M. (22 February 2020). "Hemolithin: a Meteoritic Protein containing Iron and Lithium - PDF". arXiv:2002.11688 [astro-ph.EP].
- Ferreira, Becky (28 February 2020). "A Key Ingredient for Life Has Been Found on an 'Extraterrestrial Source,' Scientists Report in this unpublished report". Vice. Retrieved 2 March 2020.
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