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Raggi, L, Bada JL, Lazcano A.  2016.  On the lack of evolutionary continuity between prebiotic peptides and extant enzymes. Physical Chemistry Chemical Physics. 18:20028-20032.   10.1039/c6cp00793g   AbstractWebsite

The significance of experiments that claim to simulate the properties of prebiotic small peptides and polypeptides as models of the polymers that may have preceded proteins is critically addressed. As discussed here, most of these experiments are based only on a small number of a larger set of amino acids that may have been present in the prebiotic environment, supported by both experimental simulations and the repertoire of organic compounds reported in carbonaceous chondrites. Model experiments with small peptides may offer some insights into the processes that contributed to generate the chemical environment leading to the emergence of informational oligomers, but not to the origin of proteins. The large body of circumstantial evidence indicating that catalytic RNA played a key role in the origin of protein synthesis during the early stages of cellular evolution implies that the emergence of the genetic code and of protein biosynthesis are no longer synonymous with the origin of life. Hence, reports on the abiotic synthesis of small catalytic peptides under potential prebiotic conditions do not provide information on the origin of triplet encoded protein biosynthesis, but in some cases may serve as models to understand the properties of the earliest proteins.

Rivas, M, Becerra A, Pereto J, Bada JL, Lazcano A.  2011.  Metalloproteins and the Pyrite-based Origin of Life: A Critical Assessment. Origins of Life and Evolution of Biospheres. 41:347-356.   10.1007/s11084-011-9238-1   AbstractWebsite

We critically examine the proposal by W chtersh user (Prokaryotes 1: 275-283, 2006a, Philos Trans R Soc Lond B Biol Sci 361: 787-1808, 2006b) that putative transition metal binding sites in protein components of the translation machinery of hyper-thermophiles provide evidence of a direct relationship with the FeS clusters of pyrite and thus indicate an autotrophic origin of life in volcanic environments. Analysis of completely sequenced cellular genomes of Bacteria, Archaea and Eucarya does not support the suggestion by W chtersh user (Prokaryotes 1: 275-283, 2006a, Philos Trans R Soc Lond B Biol Sci 361: 787-1808, 2006b) that aminoacyl-tRNA synthetases and ribosomal proteins bear sequence signatures typical of strong covalent metal bonding whose absence in mesophilic species reveals a process of adaptation towards less extreme environments.

Robertson, KJ, Williams PM, Bada JL.  1987.  Acid-Hydrolysis of Dissolved Combined Amino-Acids in Seawater - a Precautionary Note. Limnology and Oceanography. 32:996-997.Website
Rosa, C, Zeh J, George JC, Botta O, Zauscher M, Bada J, O'Hara TM.  2013.  Age estimates based on aspartic acid racemization for bowhead whales (Balaena mysticetus) harvested in 1998-2000 and the relationship between racemization rate and body temperature. Marine Mammal Science. 29:424-445.   10.1111/j.1748-7692.2012.00593.x   AbstractWebsite

Fifty-two eyes were collected and analyzed to estimate ages of 42 bowhead whales using the aspartic acid racemization aging technique. Between-eye and within-eye variance components for the ratio of the D and L optical isomers (D/L ratio) were estimated via analysis of variance using multiple measurements from nine whales with both eyes sampled and analyzed. For whales with more than one (D/L)(act) value, an inverse variance weighted average of the values was used as (D/L)(act) for the whale. Racemization rate (k(Asp)) and D/L ratio at birth (D/L)(0) were estimated using (D/L)(act) from 27 bowhead whales with age estimates based on baleen or ovarian corpora data and two term fetuses. The estimates were k(Asp) = 0.977x10(-3)/yr and (D/L)(0) = 0.0250. The nonlinear least squares analysis that produced these estimates also estimated female age at sexual maturity as ASM=25.86yr. SE(age) was estimated via a bootstrap that took into account the SE of (D/L)(act) and the variances and covariance of k(Asp) and (D/L)(0). One male exceeded 100yr of age; the oldest female was 88. A strong linear relationship between k(Asp) and body temperature was estimated by combining bowhead data with independent data from studies of humans and fin whales. Using this relationship, we estimated k(Asp) and ASM for North Atlantic minke whales.