Cientistas provam a plausibilidade de um novo caminho para os blocos químicos construtores de vida

quinta-feira, fevereiro 02, 2012

Scientists Prove Plausibility of New Pathway to Life's Chemical Building Blocks

ScienceDaily (Jan. 31, 2012) — For decades, chemists considered a chemical pathway known as the formose reaction the only route for producing sugars essential for life to begin, but more recent research has called into question the plausibility of such thinking. Now a group from The Scripps Research Institute has proven an alternative pathway to those sugars called the glyoxylate scenario, which may push the field of pre-life chemistry past the formose reaction hurdle.

Scientists show plausibility of new pathway to life's chemical building blocks. (Credit: Copyright Michele Hogan)

The team is reporting the results of their highly successful experiments online ahead of print in the Journal of the American Chemical Society.

"We were working in uncharted territory," says Ramanarayanan ("Ram") Krishnamurthy, a Scripps Research chemist who led the research, "We didn't know what to expect but the glyoxylate scenario with respect to formation of carbohydrates is not a hypothesis anymore, it's an experimental fact."

The quest to recreate the chemistry that might have allowed life to emerge on a prehistoric Earth began in earnest in the 1950s. Since that time researchers have focused on a chemical path known as the formose reaction as a potential route from the simple, small molecules that might have been present on Earth before life began to the complex sugars essential to life, at least life as we know it now.

Read more here/Leia mais aqui: Science Daily


Exploratory Experiments on the Chemistry of the “Glyoxylate Scenario”: Formation of Ketosugars from Dihydroxyfumarate

Vasudeva Naidu Sagi, Venkateshwarlu Punna, Fang Hu, Geeta Meher, and Ramanarayanan Krishnamurthy

J. Am. Chem. Soc., Just Accepted Manuscript

DOI: 10.1021/ja211383c

Publication Date (Web): January 13, 2012

Copyright © 2012 American Chemical Society


In the context of a “glyoxylate scenario”of a primordial metabolism1, the reactions of dihydroxyfumarate (DHF) with reactive small molecule aldehydes (e.g. glyoxylate, formaldehyde, glycolaldehyde and glyceraldehyde) in water were investigated, and shown to form dihydroxyacetone, tetrulose and the two pentuloses, with almost quantitative conversion. The practically clean and selective formation of ketoses in these reactions – with no detectable admixture of aldoses – stands in stark contrast to the formose reaction, where a complex mixture of linear and branched, aldoses and ketoses are produced. These results suggest that the reaction of DHF with aldehydes could constitute a reasonable pathway for the formation of carbohydrates, and allow for alternative potential prebiotic scenarios to the formose reaction to be considered. 

The formose reaction begins with formaldehyde, thought to be a plausible constituent of a prebiotic world, going through a series of chemical transformation leading to simple and then more complex sugars, including ribose, which is a key building block in DNA and RNA.

But as chemists continued to study the formose reaction they realized that the chemistry involved is quite messy, producing lots of sugars with no apparent biological use and only the tiniest bit of ribose. As such experimental results mounted, the plausibility of the formose reaction as the prebiotic sugar builder came into question. But the problem was that no one had established a reasonable alternative.


Subscription or payment needed/Requer assinatura ou pagamento: Journal of American Chemical Society