A Possible Prebiotic Ancestry of Porphyrin-Type Protein Cofactors

Pleyer, Hannes Lukas; Strasdeit, Henry; Fox, S. W.

doi:10.1007/s11084-018-9567-4

Cited by 25 publications

(26 citation statements)

References 67 publications

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“…The relatively fast (partial) racemization of an amino acid at a temperature as low as 35°C might seem surprising. But, it is well known that wet‒dry cycles, such as used in the loading process described here, can greatly accelerate chemical reactions (Fox et al ., 2018; Pleyer et al ., 2018). The presence of Iva apparently reduced the racemization rate of L-Ala to a moderate extent.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, some assume that enantioenriched extraterrestrial compounds such as Iva could have triggered the evolution of biological homochirality, which is an essential feature of life as we know it (Barron, 2008). On the early Earth, rock pools on active volcanic islands could have been favourable locations for the formation of and interaction between prebiotic organic molecules (Fox and Strasdeit, 2013; Fox et al ., 2018; Pleyer et al ., 2018). Before permanent continents existed, volcanic islands were the only dry land, which probably allowed large amounts of organic compounds to accumulate in high concentrations.…”

Section: Introductionmentioning

confidence: 99%

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Acceleration of amino acid racemization by isovaline: possible implications for homochirality and biosignature search

Fox

Gspandl

Wenng

2020

International Journal of Astrobiology

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In nature, abiotically formed amino acids are usually racemic. However, this is not true for the α,α-dialkyl amino acid isovaline (Iva), which has an L-enantiomeric excess in some specimens of carbonaceous meteorites. On the early Earth and Mars, such meteorites were sources of amino acids, including Iva. Therefore, a connection may exist between the possible chiral influence of non-racemic Iva and the origin of biological homochirality. On the surface of a young terrestrial planet, amino acids can be chemically altered in many ways. For example, high temperatures from geothermal heating can lead to racemization. Four billion years ago, active volcanism and volcanic islands provided suitable conditions for such reactions and perhaps even for early microbial life on Earth. In the current study, we investigated the influence of D- and L-Iva on the thermal racemization of L-alanine (L-Ala) and L-2-aminobutyric acid (L-Abu) in a simulated hot volcanic environment. The amino acids were intercalated in the clay mineral calcium montmorillonite (SAz-1). While Iva was resistant to racemization, partial racemization was observed for Ala and Abu after 8 weeks at 150°C. The experimental results – for example, accelerated racemization in the presence of Iva and different influences of the Iva enantiomers – suggest that the amino acid molecules interacted with each other, possibly in hydrogen-bonded dimers. Accelerated racemization of amino acids could have been an obstacle to the development of homochirality. Besides, it is also detrimental to the use of homochirality as a biosignature, for example, in the search for microbial life on Mars.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Acceleration of amino acid racemization by isovaline: possible implications for homochirality and biosignature search

Fox

Gspandl

Wenng

2020

International Journal of Astrobiology

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“…He pointed out that at times, false positive results are generated during such remote searches. These false positive bio-signals may be of abiotic nature-for example, although porphyrins, in particular metalloporphyrins, are often thought to be of biological origin, the very same molecules could also be made abiotically [31,47,48], thus giving the impression of the presence of tentative cellular life forms. Since there are many such molecules (e.g., methane; see Kotsyurbenko below) that have an abiotic origin, these cannot be excluded, meaning that the risk of misinterpretations is ever-present [49].…”

Section: Bio-signalsmentioning

confidence: 99%

Molecules to Microbes

Jheeta

2020

Sci

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How did life begin on Earth? And is there life elsewhere in the Cosmos? Challenging questions, indeed. The series of conferences established by NoR CEL in 2013 addresses these very questions. This paper comprises a summary report of oral presentations that were delivered by NoR CEL’s network members during the 2018 Athens conference and, as such, disseminates the latest research which they have put forward. More in depth material can be found by consulting the contributors referenced papers. Overall, the outcome of this conspectus on the conference demonstrates a case for the existence of “probable chemistry” during the prebiotic epoch.

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“…He pointed out that at times, false positive results are generated during such remote searches. These false positive bio-signals may be of abiotic nature-for example, although porphyrins, in particular metalloporphyrins, are often thought to be of biological origin, the very same molecules could also be made abiotically [31,47,48], thus giving the impression of the presence of tentative cellular life forms. Since there are many such molecules (e.g., methane and see Kotsyurbenko below) that have an abiotic origin, these cannot be excluded, meaning that the risk of misinterpretations is continually ever-present [49].…”

Section: Bio-mentioning

confidence: 99%

Molecules to Microbes

Jheeta¹

2020

Sci

View full text Add to dashboard Cite

How did life begin on Earth? And is there life elsewhere in the Cosmos? Challenging questions, indeed. The series of conferences established by NoR CEL in 2013, addresses these very same questions. The basis for this paper is the summary report of oral presentations that were delivered by NoR CEL’s network members during the 2018 Athens conference and, as such, disseminates the latest research which they have put forward. More in depth material can be found by consulting the contributors referenced papers. Overall, the outcome of this conspectus on the conference demonstrates a case for the existence of “probable chemistry” during the prebiotic epoch.

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A Possible Prebiotic Ancestry of Porphyrin-Type Protein Cofactors

Cited by 25 publications

References 67 publications

Acceleration of amino acid racemization by isovaline: possible implications for homochirality and biosignature search

Acceleration of amino acid racemization by isovaline: possible implications for homochirality and biosignature search

Molecules to Microbes

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