Phosphate Solubility and the Cyanate-Mediated Synthesis of Pyrophosphate

Abstract

The justification for a less alkaline primordial ocean (than present) is briefly reviewed, along with constraints on aqueous phosphate under such conditions. Based on the assumption that CaHPO(4) dihydrate determined the availability of phosphorus species, we have carried out laboratory simulations to determine equilibrium concentrations as a function of pH (in PIPES buffer) with added NaCl and CaCl(2). Consistent with expectations, solubility declines with higher pH and [CaCl(2)], but increases only slightly with [NaCl]. Significantly, PIPES shows no specific effect on the dissolution beyond its influence on pH and ionic strength. Data are also presented on the synthesis of pyrophosphate from the NaOCN/CaHPO(4).2H(2)O system, which could have provided a source of this phosphate anhydride on the early Earth.

The inevitable journey to being

“…We hypothesize that a proton flux, driven by the pH gradient amounting to five pH units, could translocate the orthophosphate anions from the ocean bathing the mound into the open subnanometric chambers walled by the crystal planes which tend to be oriented orthogonally to the outer and inner surface of the membrane (figures 4 and 5). For example, oxidation of ferrous hydroxide or further oxidation of green rust by nitrate towards the exterior (ocean side) of the inorganic membrane would have the effect of distorting the interlayers at their distal ends, opening them up to an influx of orthophosphate (HPO 4 22 ) from the Hadean Ocean [176], distortions that, as polarons, would migrate towards the membrane interior ( figure 5). At the same time, the proton flux might be relied upon to push these counterions down the steep proton gradient into the reduced interlayer where they would lodge, so blocking the proton flux [26].…”

The Fuel Cell Model of Abiogenesis: A New Approach to Origin-of-Life Simulations

“…Earth's oceans four billion years ago are thought to have been anoxic and mildly acidic (pH ~ 5-6 due to dissolved atmospheric CO2, NO and ephemeral SO2), rich in Fe 2+ , and also could have contained Ni 2+ , Mn 2+ , phosphates, nitrate, nitrite and some ferric and manganese ions (Macleod et al 1994;Russell and Hall 1997;Hagan et al, 2007;Martin et al 2007;Ducluzeau et al, 2009;Mloszewska et al, 2012;. The hydrothermal fluid produced by serpentinization would likely have been similar to modern-day hydrothermal fluids: alkaline, containing some silicate, trace Mo and W, and dissolved H2 and CH4 along with formate and a range of hydrocarbons (Proskurowski et al 2008;Mielke et al 2010;Lang et al 2010Lang et al , 2012Konn et al 2009;Charlou et al 2010).…”

Phylogenomics Supports a Cellularly Structured Urancestor

“…However, the concentration of this vital element in early Earth environments and particularly in the Archaean ocean was probably higher. Phosphorous foraging was at its minimum [Konhauser et al, 2007;Planavsky et al, 2010] and high CO 2 and lower pH might have dominated oceanic chemistry [Hagan et al, 2007;Russell et al, 2010]. However, two questions about this element are central to its involvement in the emergence of life.…”

“…Hydrogen cyanide has been proposed as an excellent prebiotic reagent for reactions leading to the synthesis of organic compounds such as amino acids, purines and pyrimidines. In addition, Hagan et al [2007] demonstrated the cyanate-mediated synthesis of pyrophosphate. There are two main scenarios where hydrogen cyanide could have been generated.…”

“…Its serpentinization could have generated reducing power, dissolved magnesium, alkaline environments and brucite [Holm and Baltscheffsky, 2011;Russell et al, 2010]. Brucite can absorb phosphorus during hydrothermal circulation [Bradley et al, 2009] and PPi can be potentially formed abiotically in these hydrothermal environments [Hagan et al, 2007;Holm and Neubeck, 2009]. Condensed phosphates have stronger binding energies to hydroxide minerals such as brucite than phosphate [Arrhenius et al, 1997].…”