Electronic Hint For Life's Origins | June 14, 2010 Issue - Vol. 88 Issue 24 | Chemical & Engineering News
Volume 88 Issue 24 | p. 39 | Concentrates
Issue Date: June 14, 2010

Electronic Hint For Life's Origins

Orbital overlap explains a counterintuitive step in a ribonucleotide synthesis feasible on an early Earth
Department: Science & Technology
Keywords: origin of life, ribonucleotides, molecular orbitals, computational chemistry
An electronic interaction (dotted line) affects the reactivity of this nucleoside.
Credit: ACS Chem. BioL.
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An electronic interaction (dotted line) affects the reactivity of this nucleoside.
Credit: ACS Chem. BioL.

Electron delocalization might have been crucial to the chemistry that started life on Earth, reports a team led by Ronald T. Raines of the University of Wisconsin, Madison, and John D. Sutherland of the University of Manchester, in England (ACS Chem. Biol., DOI: 10.1021/cb100093g). Last year, Sutherland’s team developed a recipe for ribonucleotides that offered a plausible explanation of how a primitive Earth could have spawned starter life forms based on RNA (C&EN, May 18, 2009, page 40). At one point in Sutherland’s synthesis, a phosphate group gets attached to a secondary alcohol of a nucleoside intermediate, despite the presence of a more reactive primary alcohol. Now, the team thinks they understand why. A lone pair of the oxygen from the primary alcohol interacts with the antibonding orbital of a nearby carbon-nitrogen double bond, according to a crystal structure of the nucleoside and theoretical calculations. That delocalization diminishes the primary alcohol’s reactivity, allowing phosphorylation on the secondary alcohol instead. Until now, this type of interaction hasn’t been invoked as a way to control nucleic acid reactivity, the team notes.

 
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