title: Evidence for reactive reduced phosphorus species in the early Archean ocean.
abstract: It has been hypothesized that before the emergence of modern DNA-RNA-protein life, biology evolved from an "RNA world." However, synthesizing RNA and other organophosphates under plausible early Earth conditions has proved difficult, with the incorporation of phosphorus (P) causing a particular problem because phosphate, where most environmental P resides, is relatively insoluble and unreactive. Recently, it has been proposed that during the Hadean-Archean heavy bombardment by extraterrestrial impactors, meteorites would have provided reactive P in the form of the iron-nickel phosphide mineral schreibersite. This reacts in water, releasing soluble and reactive reduced P species, such as phosphite, that could then be readily incorporated into prebiotic molecules. Here, we report the occurrence of phosphite in early Archean marine carbonates at levels indicating that this was an abundant dissolved species in the ocean before 3.5 Ga. Additionally, we show that schreibersite readily reacts with an aqueous solution of glycerol to generate phosphite and the membrane biomolecule glycerol-phosphate under mild thermal conditions, with this synthesis using a mineral source of P. Phosphite derived from schreibersite was, hence, a plausible reagent in the prebiotic synthesis of phosphorylated biomolecules and was also present on the early Earth in quantities large enough to have affected the redox state of P in the ocean. Phosphorylated biomolecules like RNA may, thus, have first formed from the reaction of reduced P species with the prebiotic organic milieu on the early Earth.
authors.affiliation: Department of Geology, University of South Florida, Tampa, FL 33620, USA. mpasek@usf.edu
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Pasek
authors.forename: Jelte P
authors.initials: JP
authors.lastname: Harnmeijer
authors.forename: Roger
authors.initials: R
authors.lastname: Buick
authors.forename: Maheen
authors.initials: M
authors.lastname: Gull
authors.forename: Zachary
authors.initials: Z
authors.lastname: Atlas
mesh_terms: D002254:Carbonates / Q000737:chemistry; D019418:Evolution, Chemical; D019419:Evolution, Planetary; D018559:Exobiology; D052203:Ferrosoferric Oxide / Q000737:chemistry; D005844:Geology; D019110:Meteoroids; D009792:Oceans and Seas; D000069497:Origin of Life; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000737:chemistry*; D010766:Phosphorylation; D012313:RNA / Q000737:chemistry*
chemical_list: D002254:Carbonates; D010758:Phosphorus; D012313:RNA; D052203:Ferrosoferric Oxide
keywords: astrobiology; exobiology; origin of life; phosphorylation; prebiotic chemistry