Hemolithin is an iron and lithium-containing protein of extraterrestrial origin according to a preprint that has not been published in a scientific journal. It was found inside two CV3 meteorites, Allende and Acfer-086. 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 The study is an extension of published and unpublished results by the teams.
Structure
Hemolithin, the newly found protein, was found, aided by the use of "state-of-the-art" mass spectrometry, to be largely composed ofglycine and hydroxyglycineamino 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 ; 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 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. "Hydroxyglycine was first detected in the meteorite Allende and this was published in 2015. At that point in time, only fragments of Hemolithin were detected. There is presented in the Hemolithin MS very clear evidence of multiple oxidations of a 17 glycine polymer: The hemolithin MS 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."
Significance
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 fromouter space instead – a process known as panspermia. Besides this possible discovery of an extraterrestrial protein, other evidences of complex chemistry 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 throughout the universe.
History
Hemolithin is the name given to a protein molecule isolated from two CV3 meteorites, Allende and Acfer-086. Its deuterium to hydrogen ratio is 26 times terrestrial which is consistent with it having formed in an interstellar molecular cloud, or later in the protoplanetary disk at the start of our solar system 4.567 billion years ago. The elements hydrogen, lithium, carbon, oxygen, nitrogen and iron that it is composed of, were all available for the first time 13 billion years ago after the first generation of massive stars ended in nucleosynthetic events. The horizontal arrow in the :File:HemolithinTimeLine-McGeochJEM-20200322.jpg|time line graph below shows, on the scale of the start of the Universe to the present, when Hemolithin could have formed and reformed. The research leading to the discovery of Hemolithin started in 2007 when another protein, one of the first to form on Earth, was observed to entrap water. That property being useful to chemistry before biochemistry on earth developed, theoretical enthalpy calculations on the condensation of amino acids were performed in gas phase space asking: “whether amino acids could polymerize to protein in space?” - they could, and their water of condensation aided their polymerization. This led to several manuscripts of isotope and mass information on Hemolithin.
