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Old Materials Resurface For "Prebiotic Soup"
AliasMarlowe writes "Stanley Miller performed the famous experiments in the 1950s showing that amino acids and other building blocks for biomolecules could be produced by passing lightning through a mix of simple hydrocarbons, water vapor, and ammonia (thought at the time to approximate the Earth's early atmosphere). Other experiments approximated the environment around volcanic eruptions, but those results were not published. Following his death last year, a former student discovered the materials from those experiments, in labelled vials. Analysis of this material indicates that the conditions around volcanic eruptions (still thought to be representative of such events in the early Earth) resulted in a higher yield of amino acids than the simple lightning experiments, and resulted in a greater variety of amino acids." Pharyngula has a discussion of the Science paper, including a graph of the amino acids produced.
Um, say what? 'Which' particular hypothesis has very little credibility? Abiogenesis? Just because it's a difficult field of study doesn't mean it is either uninteresting, unfunded or un-anything. For your edification and enjoyment a few crackpot lectures.
Faster! Faster! Faster would be better!
The distribution of amino acids is quite interesting. Eight of the amino acids (glycine, alanine, valine, serine, phenylalanine, aspartic acid, and glutamic acid) are from the 20 "standard" amino acids directly coded for in DNA. Seven more are isomers, close homologs, or simple derivatives of the standard seven (isovaline, 2-methylserine, etc.). Ornithine is not found in proteins, but is found as an intermediate both the natural synthesis and breakdown of other amino acids. It is curiously enough the only amino acid found in the vial which is a base- I would have expected more, given all the ammonia in the experiment atmosphere. I would have expected glutamine and asparagine as well, but they're pretty fragile, and if present, may have been lost in the workup.
Five are aminobutyric or aminoisobutyric acids, which are also not coded for by DNA, but are involved in biochemical processes (the best known example is gamma-aminobutryric acid, GABA, a neurotransmitter). No sulfur in the vial, so the absence of cysteine and methionine is unsurprising. Proline is absent, but in organisms, it is formed from an enzyme-catalyzed ring formation from glutamic acid, so it may not form easily in test tubes.
Phenylalanine was the only aromatic amino acid found, which is unsurprising, given the complexity- in organisms, they tend to be synthesized by multistep enzyme-catalyzed routes, and most organisms high on the food chain have lost this ability. Notably, phenylalanine seems to be present in the vial at about one-millionth the concentration of glycine, so its production is a pretty rare event. And all of the amino acids produced were racemic mixtures, whereas nearly all amino acids utilized in nature are the L-enantiomer. It is still a mystery as to when homochirality first arose.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
I don't remember what I've been told at 9th grade, but as of now (2008) there's not much about "biologists having cracked the problem of life". And unlike you, I'm constantly dealing with these matters (IAAMBAABC, where "AABC" stands for "and a biochemist").
Thanks for the nice reading which directly contradicts your opinion:
See?