{"426521":{"#nid":"426521","#data":{"type":"news","title":"Finding the Origins of Life in a Drying Puddle","body":[{"value":"\u003Cp\u003EAnyone who\u2019s ever noticed a water puddle drying in the sun has seen an environment that may have driven the type of chemical reactions that scientists believe were critical to the formation of life on the early Earth.\u003C\/p\u003E\u003Cp\u003EResearch reported July 15 in the journal \u003Cem\u003EAngewandte Chemie International Edition\u003C\/em\u003E demonstrates that important molecules of contemporary life, known as polypeptides, can be formed simply by mixing amino and hydroxy acids \u2013 which are believed to have existed together on the early Earth \u2013 then subjecting them to cycles of wet and dry conditions. This simple process, which could have taken place in a puddle drying out in the sun and then reforming with the next rain, works because chemical bonds formed by one compound make bonds easier to form with the other.\u003C\/p\u003E\u003Cp\u003EThe research supports the theory that life could have begun on dry land, perhaps even in the desert, where cycles of nighttime cooling and dew formation are followed by daytime heating and evaporation. Just 20 of these day-night, wet-dry cycles were needed to form a complex mixture of polypeptides in the lab. The process also allowed the breakdown and reassembly of the organic materials to form random sequences that could have led to the formation of the polypeptide chains that were needed for life.\u003C\/p\u003E\u003Cp\u003E\u201cThe simplicity of using hydration-dehydration cycles to drive the kind of chemistry you need for life is really appealing,\u201d said \u003Ca href=\u0022http:\/\/www.chemistry.gatech.edu\/people\/Hud\/Nicholas\u0022\u003ENicholas Hud\u003C\/a\u003E, a professor in the \u003Ca href=\u0022http:\/\/www.chemistry.gatech.edu\/\u0022\u003ESchool of Chemistry and Biochemistry\u003C\/a\u003E at the Georgia Institute of Technology, and director of the \u003Ca href=\u0022http:\/\/centerforchemicalevolution.com\/\u0022\u003ENSF\/NASA Center for Chemical Evolution\u003C\/a\u003E, which is supported by the NSF Centers for Chemical Innovation Program and the NASA Astrobiology Program. \u201cIt looks like dry land would have provided a very favorable environment for getting the chemistry necessary for life started.\u201d\u003C\/p\u003E\u003Cp\u003EOrigin-of-life scientists had previously made polypeptides from amino acids by heating them well past the boiling point of water, or by driving polymerization with activating chemicals. But the high temperatures are beyond the point at which most life could survive, and the robust availability of activating chemicals on the early Earth is questionable. The simplicity of the wet-dry cycle therefore makes it attractive to explain how peptides could have formed, Hud added.\u003C\/p\u003E\u003Cp\u003EThe idea for combining chemically similar amino acids and hydroxyl acids was inspired by the demonstration that polyesters are easy to form by repetitive hydration-dehydration cycles and the fact that esters are activated to attack by the amino group of amino acids. The potential importance of this reaction in the earliest stages of life is supported by studies of meteorites, which revealed that both compounds would have been present on the prebiotic Earth.\u003C\/p\u003E\u003Cp\u003EHydroxy acids combine to form polyester, better known as a synthetic textile fiber, and that reaction requires less energy than formation of the amide bonds needed to create peptides from amino acids. In the wet-dry cycles, formation of polyester comes first \u2013 which then facilitates the more difficult peptide formation, Hud said.\u003C\/p\u003E\u003Cp\u003E\u201cThe ester linkages that we are making in the polyester can serve as an activating agent formed within the solution,\u201d he explained. \u201cOver the course of a very simple chemical evolution, the polymers progress from having hydroxy acids with ester linkages to amino acids with peptide linkages. The hydroxy acids are gradually replaced through the wet and dry cycles because the ester bonds holding them together are not as stable as the peptide bonds.\u201d\u003C\/p\u003E\u003Cp\u003EExperimentally, graduate student Sheng-Sheng Yu put the amino and hydroxy acid mixtures through 20 wet-dry cycles to produce molecules that are a mixture of polyesters and peptides, containing as many as 14 units. After just three cycles, and at temperatures as low as 65 degrees Celsius, peptides consisting of two and three units began to form. Postdoctoral fellow Jay Forsythe confirmed the chemical structures using NMR mass spectrometry.\u003C\/p\u003E\u003Cp\u003E\u201cWe allowed the peptide bonds to form because the ester bonds lowered the energy barrier that needed to be crossed,\u201d Hud added.\u003C\/p\u003E\u003Cp\u003EOn the early Earth, those cycles could have taken 20 days and nights \u2013 or perhaps much longer if the heating and drying cycles corresponded to seasons of the year.\u003C\/p\u003E\u003Cp\u003EBeyond easily forming the polypeptides, the wet-dry process has an additional advantage. It allows compounds like peptides to be regularly broken apart and reformed, creating new structures with randomly-ordered amino acids. This ability to recycle the amino acids not only conserves organic material that may have been in short supply on the early Earth, but also provides the potential for creating more useful combinations.\u003C\/p\u003E\u003Cp\u003EA combination of hydroxy and amino acids likely existed in the prebiotic soup of the early Earth, but analyzing such a \u201cmessy\u201d reaction was challenging, Hud said. \u201cWe were led into this idea that a mixture might work better than separate components,\u201d he explained. \u201cIt might have been messy at the start, but it\u2019s easier to get going than a pristine chemical reaction.\u201d\u003C\/p\u003E\u003Cp\u003EBeyond helping explain how life might have started, the wet-dry cycles could also provide a new way to synthesize polypeptides. Existing techniques produce the chemicals through genetic engineering of microorganisms, or through synthetic organic chemistry. The wet-dry cycling could provide a simpler and more sustainable water-based process for producing these chemicals.\u003C\/p\u003E\u003Cp\u003EThe demonstration of peptide formation opens the door to asking other questions about how life may have gotten going in prebiotic times, said Ramanarayanan Krishnamurthy, a member of the research team and an associate professor of chemistry at the Scripps Research Institute. Future studies will include a look at the sequences formed, whether there are sequences favored by the process, and what sequences might result. The process could ultimately lead to reactions able to continue without the wet-dry cycles.\u003C\/p\u003E\u003Cp\u003E\u201cIf this process were repeated many times, you could grow up a peptide that could acquire a catalytic property because it had reached a certain size and could fold in a certain way,\u201d Krishnamurthy said. \u201cThe system could begin to develop certain emergent characteristics and properties that might allow it to self-propagate.\u201d\u003C\/p\u003E\u003Cp\u003EIn addition to those already named, the paper\u2019s authors include Irena Mamajanov, Martha A Grover, and Facundo M. Fern\u00e1ndez, all from Georgia Tech.\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis research was\u0026nbsp;supported by\u0026nbsp;the NSF Centers for Chemical Innovation Program and the NASA Astrobiology Program under the NSF\/NASA Center for Chemical Evolution\u0026nbsp;under grant number CHE-1004570. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NSF or NASA.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Jay G. Forsythe, et al., \u201cEster-Mediated Amide Bond Formation Driven by Wet-Dry Cycles: A Possible Path to Polypeptides on the Prebiotic Earth,\u201d (Angewandte Chemie International Edition, 2015).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EResearch News\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E177 North Avenue\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia 30332-0181 USA\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contact\u003C\/strong\u003E: John Toon (404-894-6986) (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\u003Cbr \/\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EAnyone who\u2019s ever noticed a water puddle drying in the sun has seen an environment that may have driven the type of chemical reactions that scientists believe were critical to the formation of life on the early Earth.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Cycles of wet and dry conditions may have driven the type of chemical reactions that scientists believe were critical to the formation of life on the early Earth."}],"uid":"27303","created_gmt":"2015-07-19 20:44:46","changed_gmt":"2016-10-08 03:19:12","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2015-07-20T00:00:00-04:00","iso_date":"2015-07-20T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"426481":{"id":"426481","type":"image","title":"Producing polypeptides","body":null,"created":"1449254342","gmt_created":"2015-12-04 18:39:02","changed":"1475895165","gmt_changed":"2016-10-08 02:52:45","alt":"Producing polypeptides","file":{"fid":"202763","name":"wet-dry1344.jpg","image_path":"\/sites\/default\/files\/images\/wet-dry1344_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/wet-dry1344_0.jpg","mime":"image\/jpeg","size":881544,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/wet-dry1344_0.jpg?itok=32-IN6FE"}},"426491":{"id":"426491","type":"image","title":"Producing polypeptides2","body":null,"created":"1449254342","gmt_created":"2015-12-04 18:39:02","changed":"1475895165","gmt_changed":"2016-10-08 02:52:45","alt":"Producing polypeptides2","file":{"fid":"202764","name":"wet-dry1354.jpg","image_path":"\/sites\/default\/files\/images\/wet-dry1354_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/wet-dry1354_0.jpg","mime":"image\/jpeg","size":966634,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/wet-dry1354_0.jpg?itok=dPQYAHvI"}},"426501":{"id":"426501","type":"image","title":"Producing polypeptides3","body":null,"created":"1449254342","gmt_created":"2015-12-04 18:39:02","changed":"1475895165","gmt_changed":"2016-10-08 02:52:45","alt":"Producing polypeptides3","file":{"fid":"202765","name":"wet-dry1390.jpg","image_path":"\/sites\/default\/files\/images\/wet-dry1390_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/wet-dry1390_0.jpg","mime":"image\/jpeg","size":1234180,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/wet-dry1390_0.jpg?itok=UKO6Wz3a"}}},"media_ids":["426481","426491","426501"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"141","name":"Chemistry and Chemical Engineering"},{"id":"146","name":"Life Sciences and Biology"},{"id":"135","name":"Research"}],"keywords":[{"id":"109501","name":"amino acids"},{"id":"10339","name":"center for chemical evolution"},{"id":"12661","name":"Early Earth"},{"id":"4504","name":"Nicholas Hud"},{"id":"135891","name":"origin-of-life"},{"id":"135861","name":"polypeptides"}],"core_research_areas":[{"id":"39441","name":"Bioengineering and Bioscience"},{"id":"39491","name":"Renewable Bioproducts"}],"news_room_topics":[{"id":"71911","name":"Earth and Environment"},{"id":"71881","name":"Science and Technology"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}