The uptake of phosphorus by brucite during hydrothermal circulation has lead Bradley et al. (2009) to propose that the utilization of glycosyl head groups instead of phosphatidyl head groups by bacteria constitutes a strategy for conservation of scarce phosphorus. Condensed KPT-330 order phosphates have stronger binding energies to hydroxide minerals like brucite than orthophosphate (Arrhenius et al. 1997), in the same way as polynucleotides bind stronger than mononucleotides (Holm et al. 1993). This means that the condensed phosphates have the potential to (outcompete orthophosphate and) concentrate on the mineral surfaces. Inorganic pyro- and polyphosphates are used for energy transfer

and storage in many microorganisms, and it has been proposed that the chemical energy stored in this type of inorganic molecules has been used by primitive forms of life on the early Earth (Baltscheffsky and Baltscheffsky 1994). Despite the general scarcity of phosphorus on Earth, such compounds could have been produced in the prebiotic world by several possible pathways. Prebiotic Pyrophosphate Formation Wheat et al. (1996) have estimated that ridge-axis and ridge-flank hydrothermal processes Fedratinib supplier in the ocean floor in combination today remove about 50% of the global input of dissolved phosphorus from rivers into oceanic crust. Bodeï et al. (2008) have shown that phosphate is

strongly enriched as authigenic phases in the basal sedimentary layer on top of the basaltic basement, the source of phosphorus being primarily the basalts underneath. Under standard temperature conditions (25°C), apatite (Ca-orthophosphate) forms as a single phase at pH 9 or higher in a sterile seawater medium. However, in the pH range 7–9 primarily the mineral whitlockite (Ca18Mg2H2(PO4)14 is formed under the same temperature conditions (Gedulin and Arrhenius 1994). Preformed crystals of apatite placed in a neutral or slightly alkaline sterile solution with the Mg/Ca ratio of seawater

convert to whitlockite. Abbona and Franchini-Angela (1990) have also shown that amorphous calcium phosphate converts to whitlockite above the Mg/Ca molar ratio 0.8. It has C-X-C chemokine receptor type 7 (CXCR-7) long been known that hydrogen containing phosphates like whitlockite and newberyite at heating react to form pyrophosphate and water (Sales et al. 1993; Gedulin and Arrhenius 1994). Low water activity in the system promotes the pyrophosphate formation (Russell and Hall 1997). The phosphate condensation is due to the protonation of the phosphate. At heating, the hydrogen reacts with one of the oxygen ligands of the phosphorus and leaves as water. As a response, the structure of the orthophosphate rearranges to form one or more anhydride P-O-P bonds (Arrhenius et al. 1997), i.e. the backbone of condensed phosphates like pyrophosphate. A seemingly alternative pathway for pyrophosphate formation would be oxidation of the phosphide mineral schreibersite (Fe,Ni)3P.