Phosphate Activation via Reduced Oxidation State Phosphorus (P). Mild Routes to Condensed-P Energy Currency Molecules.

Terence Kee,Zachary Atlas,Matthew Pasek,Nichola Cosgrove,Katie Marriott,David Bryant,Claire Cousins,Barry Herschy

doi:10.3390/life3030386

Terence Kee, Zachary Atlas + Show 6 more

Open Access

https://doi.org/10.3390/life3030386

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Abstract

The emergence of mechanisms for phosphorylating organic and inorganic molecules is a key step en route to the earliest living systems. At the heart of all contemporary biochemical systems reside reactive phosphorus (P) molecules (such as adenosine triphosphate, ATP) as energy currency molecules to drive endergonic metabolic processes and it has been proposed that a predecessor of such molecules could have been pyrophosphate [P2O74−; PPi(V)]. Arguably the most geologically plausible route to PPi(V) is dehydration of orthophosphate, Pi(V), normally a highly endergonic process in the absence of mechanisms for activating Pi(V). One possible solution to this problem recognizes the presence of reactive-P containing mineral phases, such as schreibersite [(Fe,Ni)3P] within meteorites whose abundance on the early Earth would likely have been significant during a putative Hadean-Archean heavy bombardment. Here, we propose that the reduced oxidation state P-oxyacid, H-phosphite [HPO32−; Pi(III)] could have activated Pi(V) towards condensation via the intermediacy of the condensed oxyacid pyrophosphite [H2P2O52−; PPi(III)]. We provide geologically plausible provenance for PPi(III) along with evidence of its ability to activate Pi(V) towards PPi(V) formation under mild conditions (80 °C) in water.

Highlights

Amongst the most important and ubiquitous energy-currency molecules of contemporary biochemistry are activated phosphorus (P) species such as phosphocreatine, phosphoenol pyruvate, and adenosine triphosphate (ATP) [1]
Water was purified by ion exchange on a Purite Select Analyst (PSA) reverse osmosis-deionization system (Purite Ltd., Oxford, UK)
A few percent PPi(III) remain which can be allowed to hydrolyze by raising the pH to 8 leaving a solution of approximately 46% of total phosphorus being present as PPi(III–V)

Summary

Introduction

Amongst the most important and ubiquitous energy-currency molecules of contemporary biochemistry are activated phosphorus (P) species such as phosphocreatine, phosphoenol pyruvate, and adenosine triphosphate (ATP) [1]. These molecules are able to selectively discharge tranches of energy We introduce a method of activating Pi(V) based on the reduced oxidation form of P, H-phosphite, Pi(III) As part of this mechanism, the condensed oxyacids pyrophosphite [PPi(III); H2P2O52−] and isohypophosphate [PPi(III–V); H2P2O63−] are seen as playing significant roles. Plausible provenance for both Pi(III) and PPi(III) along with evidence of the ability of the latter to provide a low energy route to PPi(V) via activation of Pi(V) towards condensation in the presence of divalent metals

Materials and General Analytical Methods

Hveradalur Lake Geothermal Field Experiments

Pyrophosphite Formation and Geological Provenance

Conclusions