Chemical, Thermal, and Radiation Resistance of an Iron Porphyrin: A Model Study of Biosignature Stability.

Metal complexes of porphyrins and porphyrin-type compounds are ubiquitous in all three domains of life, with hemes and chlorophylls being the best-known examples. Their diagenetic transformation products are found as geoporphyrins, in which the characteristic porphyrin core structure is retained and which can be up to 1.1 billion years old.

A Possible Prebiotic Ancestry of Porphyrin-Type Protein Cofactors.

In previous experiments that simulated conditions on primordial volcanic islands, we demonstrated the abiotic formation of hydrophobic porphyrins. The present study focused on the question whether such porphyrins can be metalated by prebiotically plausible metal ion sources. We used water-insoluble octaethylporphyrin (Hoep) as a model compound.

Influence of the metal ion on the enzyme activity and kinetics of PepA from Lactobacillus delbrueckii.

The aminopeptidase A (PepA; EC 3.4.11.

Inhabited or Uninhabited? Pitfalls in the Interpretation of Possible Chemical Signatures of Extraterrestrial Life.

The "Rare Earth" hypothesis-put forward by Ward and Brownlee in their 2000 book of the same title-states that prokaryote-type organisms may be common in the universe but animals and higher plants are exceedingly rare. If this idea is correct, the search for extraterrestrial life is essentially the search for microorganisms. Various indicators may be used to detect extant or extinct microbial life beyond Earth.

The Influence of Mineral Matrices on the Thermal Behavior of Glycine.

On the Hadean-Early Archean Earth, the first islands must have provided hot and dry environments for abiotically formed organic molecules. The heat sources, mainly volcanism and meteorite impacts, were also available on Mars during the Noachian period. In recent work simulating this scenario, we have shown that neat glycine forms a black, sparingly water-soluble polymer ("thermomelanoid") when dry-heated at 200 °C under pure nitrogen.