Posted by: Dan | October 30, 2006

Amino Acid Formation Under Presumptive Hadean, Volcanic, Hydrothermal Conditions

There’s an interesting article on the origin of life that I almost missed in Friday’s issue of Science, titled “{alpha}-Hydroxy and {alpha}-Amino Acids Under Possible Hadean, Volcanic Origin-of-Life Conditions.” Abstract:

To test the theory of a chemoautotrophic origin of life in a volcanic, hydrothermal setting, we explored mechanisms for the buildup of bio-organic compounds by carbon fixation on catalytic transition metal precipitates. We report the carbon monoxide-dependent formation of carbon-fixation products, including an ordered series of alpha-hydroxy and alpha-amino acids of the general formula R-CHA-COOH (where R is H, CH3,C2H5,orHOCH2 and A is OH or NH2) by carbon fixation at 80 degrees to 120 degrees C, catalyzed by nickel or nickel,iron precipitates with carbonyl, cyano, and methylthio ligands as carbon sources, with or without sulfido ligands. Calcium or magnesium hydroxide was added as a pH buffer. The results narrow the gap between biochemistry and volcanic geochemistry and open a new gateway for the exploration of a volcanic, hydrothermal origin of life.


Amino acids are critical to the origins of cellular life, but of course the most plausible theory to-date is the RNA World Hypothesis, which invokes the formation of ribonucleic acids as the first crucial step from the pre-biotic world to a cellular one. So it’s hard to know where to place the findings in this paper, other than in the realm of the classic experiment by Miller (1953).

Still, it DOES illustrate once again the capacity for carbon fixation in pre-biotic settings, and supports the proposal of a non-extraordinary and thus plausible mechanism for the advent of organic chemistry, which flies in the face of creationist claims.

But what, specifically, does this paper conclude?:

This discussion concludes with the evolutionary context of our results. {alpha}-Hydroxy and a-amino acids are chelating ligands for transition metals. The synthesis of these compounds under presumptive Hadean, volcanic, hydrothermal conditions therefore supports the notion that the earliest mechanism of reproduction and evolution was based on positive (autocatalytic) feedback, whereby certain synthetic products led to ligand-accelerated transition metal catalysis that greatly increased the rates of the synthetic reactions, the activities of their products, and the spectrum of feedback possibilities, with an eventual emergence of metalloenzymes.

More on a couple RNA World articles later in the week…

References:

  • alpha-Hydroxy and alpha-amino acids under possible Hadean, volcanic origin-of-life conditions. Huber C, Wachtershauser G. Science. 2006 Oct 27; 314(5799):630-2. Pubmed

Responses

  1. […] Science has a comment and response to an article that I blogged on a few months ago, concerning the formation of amino acids under presumptive Hadean conditions. The comment, by Bada et al., focuses on the (un)availability of KCN and CO under the Hadean […]


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