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Bada, JL.  2004.  How life began on Earth: a status report. Earth and Planetary Science Letters. 226:1-15.   10.1016/j.epsl.2004.07.036   AbstractWebsite

There are two fundamental requirements for life as we know it, liquid water and organic polymers, such as nucleic acids and proteins. Water provides the medium for chemical reactions and the polymers carry out the central biological functions of replication and catalysis. During the accretionary phase of the Earth, high surface temperatures would have made the presence of liquid water and an extensive organic carbon reservoir unlikely. As the Earth's surface cooled, water and simple organic compounds, derived from a variety of sources, would have begun to accumulate. This set the stage for the process of chemical evolution to begin in which one of the central facets was the synthesis of biologically important polymers, some of which had a variety of simple catalytic functions. Increasingly complex macromolecules were produced and eventually molecules with the ability to catalyze their own imperfect replication appeared. Thus began the processes of multiplication, heredity and variation, and this marked the point of both the origin of life and evolution. Once simple self-replicating entities originated, they evolved first into the RNA World and eventually to the DNA/Protein World, which had all the attributes of modern biology. If the basic components water and organic polymers were, or are, present on other bodies in our solar system and beyond, it is reasonable to assume that a similar series of steps that gave rise of life on Earth could occur elsewhere. (C) 2004 Elsevier B.V. All rights reserved.

Bada, JL, Miller SL.  1970.  Kinetics and Mechanism of Reversible Nonenzymatic Deamination of Aspartic Acid. Journal of the American Chemical Society. 92:2774-&.   10.1021/ja00712a031   Website
Bada, JL, Wang XYS, Hamilton H.  1999.  Preservation of key biomolecules in the fossil record: current knowledge and future challenges. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences. 354:77-86.   10.1098/rstb.1999.0361   AbstractWebsite

We have developed a model based on the analyses of modern and Pleistocene eggshells and mammalian bones which can be used to understand the preservation of amino acids and other important biomolecules such as DNA in fossil specimens. The model is based on the following series of diagenetic reactions and processes involving amino acids: the hydrolysis of proteins and the subsequent loss of hydrolysis products from the fossil matrix with increasing geologic age; the racemization of amino acids which produces totally racemized amino acids in 10(5)-10(6) years in most environments on the Earth; the introduction of contaminants into the fossil that lowers the enantiomeric (D:L) ratios produced via racemization; and the condensation reactions between amino acids, as well as other compounds with primary amino groups, and sugars which yield humic acid-like polymers. This model was used to evaluate whether useful amino acid and DNA sequence information is preserved in a variety of human, amber-entombed insect and dinosaur specimens. Most skeletal remains of evolutionary interest with respect to the origin of modern humans are unlikely to preserve useful biomolecular information although those from high latitude sites may be an exception. Amber-entombed insects contain well-preserved unracemized amino acids, apparently because of the anhydrous nature of the amber matrix, and thus may contain DNA fragments which have retained meaningful genetic information. Dinosaur specimens contain mainly exogenous amino acids, although traces of endogenous amino acids may be present in some cases. Future ancient biomolecule research which takes advantage of new methologies involving, for example, humic acid cleaving reagents and microchip-based DNA-protein detection and sequencing, along with investigations of very slow biomolecule diagenetic reactions such as the racemization of isoleucine at the beta-carbon, will lead to further enhancements of our understanding of biomolecule preservation in the fossil record.

Bada, JL, Schroeder RA.  1975.  Amino-Acid Racemization Reactions and Their Geochemical Implications. Naturwissenschaften. 62:71-79. AbstractWebsite
Bada, JL, Mitchell E, Kemper B.  1983.  Aspartic-Acid Racemization in Narwhal Teeth. Nature. 303:418-420.   10.1038/303418a0   Website
Bada, JL, Miller SL, Zhao MX.  1995.  The Stability of Amino-Acids at Submarine Hydrothermal Vent Temperatures. Origins of Life and Evolution of the Biosphere. 25:111-118.   10.1007/bf01581577   AbstractWebsite

It has been postulated that amino acid stability at hydrothermal vent temperatures is controlled by a metastable thermodynamic equilibrium rather than by kinetics. Experiments reported here demonstrate that the amino acids are irreversibly destroyed by heating at 240 degrees C and that quasi-equilibrium calculations give misleading descriptions of the experimental observations. Equilibrium thermodynamic calculations are not applicable to organic compounds under high-temperature submarine vent conditions.

Bada, J, Brown SE, Masters PM.  1980.  age determination of marine mammaks based on aspartic acid racemization in teeth and lens nucleus. Rep.International Whaling comisison (Special issue). 3:113-118.
Bada, JL, Peterson RO, Schimmelmann A, Hedges REM.  1990.  Moose Teeth as Monitors of Environmental Isotopic Parameters. Oecologia. 82:102-106.   10.1007/bf00318540   Website
Bada, JL, Protsch R.  1973.  Racemization Reaction of Aspartic-Acid and Its Use in Dating Fossil Bones - (Olduvai Gorge 5,000-70,000-Years-Old Range Hominids). Proceedings of the National Academy of Sciences of the United States of America. 70:1331-1334.   10.1073/pnas.70.5.1331   Website
Bada, JL.  1985.  Aspartic-Acid Racemization Ages of California Paleoindian Skeletons. American Antiquity. 50:645-647.   10.2307/280327   Website
Bada, JL, Miller SL.  1969.  Kinetics and Mechanism of Nonenzymatic Reversible Deamination of Aspartic Acid. Journal of the American Chemical Society. 91:3946-&.   10.1021/ja01042a047   Website
Bada, JL.  1998.  Biogeochemistry of organic nitrogen compounds. Nitrogen-Containing Macromolecules in the Bio- and Geosphere. 707( Stankiewicz BA, VanBergen PF, Eds.).:64-73., Washington: Amer Chemical Soc Abstract

Nitrogen containing organic compounds represent the second most abundant reservoir of nitrogen on the surface of the Earth. However, the organic compounds that make up this global nitrogen pool are not well characterized. Although amino acids and the nitrogenous bases of nucleic acids make up only a few percent of the total organic nitrogen reservoir, the geochemical reactions of these compounds have been extensively studied. Because hydrolysis reactions are rapid on the geologic time scale, both proteins and nucleic acids (DNA and RNA) are not preserved for more than 10(3) to 10(5) years in most environments. The racemization reaction of amino acids converts the L-amino acids present in the biosphere into a racemic mixture (D/L amino acid ratio = 1.0) in the geosphere in less than 10(6) years. Anhydrous conditions, such as those that may be associated with amber entombed insects, may retard both biopolymer hydrolysis and racemization. Condensation reactions between amino acids and sugars, including sugars at apurinic sites in nucleic acid fragments, likely result in the incorporation of these compounds into geopolymers such as humic acids. Although rearrangement reactions in geopolymers may scramble the original molecular structures, part of the global organic nitrogen inventory was originally derived from amino acids and nucleic acid bases.

Bada, JL, Brown SE.  1980.  Amino-Acid Racemization in Living Mammals - Biochronological Applications. Trends in Biochemical Sciences. 5:R3-R5.   10.1016/s0968-0004(80)80800-0   AbstractWebsite
Bada, J.  1983.  Amino Acid Racemization dating of fossil bones from Zhouk. China Excahnge News. 11:4-6.
Bada, J, Herman B, Payan IL, Man E.  1989.   Amino Acid Racemization in bone and boiling of the german emperor Lothar I. Applied Geochemistry. 4
Bada, JL.  1972.  Kinetics of Racemization of Amino-Acids as a Function of Ph. Journal of the American Chemical Society. 94:1371-&.   10.1021/ja00759a064   Website
Bada, JL, Lazcano A.  2002.  Origin of life - Some like it hot, but not the first biomolecules. Science. 296:1982-1983.   10.1126/science.1069487   Website
Bada, JL, Miller SL.  1968.  Equilibrium Constant for Reversible Deamination of Aspartic Acid. Biochemistry. 7:3403-&.   10.1021/bi00850a014   Website
Bada, JL, Chalmers JH, Cleaves HJ.  2016.  Is formamide a geochemically plausible prebiotic solvent? Physical Chemistry Chemical Physics. 18:20085-20090.   10.1039/c6cp03290g   AbstractWebsite

From a geochemical perspective, significant amounts of pure formamide (HCONH2) would have likely been rare on the early Earth. There may have been mixed formamide-water solutions, but even in the presence of catalyst, solutions with >= 20 weight% water in formamide would not have produced significant amounts of prebiotic compounds. It might be feasible to produce relatively pure formamide by a rare occurrence of freezing formamide/water mixtures at temperatures lower than formamide's freezing point (2.55 degrees C) but greater than the freezing point of water. Because of the high density of formamide ice it would have sunk and accumulated at the bottom of the solution. If the remaining water froze on the surface of this ice, and was then removed by a sublimation-ablation process, a small amount of pure formamide ice might have been produced. In addition a recent report suggested that similar to 85 weight% formamide could be prepared by a geochemical type of fractional distillation process, offering another possible route for prebiotic formamide production.

Bada, JL.  1982.  Racemization of Amino-Acids in Nature. Interdisciplinary Science Reviews. 7:30-46.Website
Bada, JL, Zhao MX, Steinberg S, Ruth E.  1986.  Isoleucine Stereoisomers on the Earth. Nature. 319:314-316.   10.1038/319314a0   Website