Pyrophosphate synthesis from phospho(enol)pyruvate catalyzed by precipitated magnesium phosphate with ?enzyme-like? activity

Abstract

The enzyme-like kinetic properties of precipitated magnesium phosphate as a catalyst for formation of pyrophosphate (PPi) from phospho(enol)pyruvate (PEP) are described. This synthesis occurs at a low temperature (37 degrees C) and represents a model that may help us understand the relevance to chemical evolution of minerals as ancient catalysts whose functions could have been taken over by contemporary enzymes. An insoluble Pi.Mg matrix was formed in a medium with 80% of the water replaced by dimethyl sulfoxide as a way of simulating conditions in a drying pond. Phospho(enol)pyruvate adsorbs onto the Pi.Mg surface according to a Langmuir isotherm, and the PEP concentration dependence of PPi formation follows a Michaelian-like function. A yield of 33% for transformation of the initially adsorbed PEP into PPi was attained after 4 days of incubation with equimolecular concentrations of Pi, MgCl2, and PEP. The magnesium concentration dependence for Pi and Mg precipitation, for adsorption of PEP onto solid Pi.Mg, and for PPi formation showed complex cooperative behavior. These results taken as a whole lead to the conclusion that the Pi.Mg surface not only provides a reactant for PPi formation but also catalyzes the reaction.

Biomimetic phosphoryl transfer catalysed by iron(II)-mineral precipitates

“…Very high concentrations of monovalent metal ions (Ͼ6 mol/L) also promote phosphoryl transfer (Herschlag and Jencks, 1986). There is also a report of metal ion-catalysis of phosphoryl transfer from phosphoenolpyruvate to inorganic phosphate (Hermes-Lima and Vieyra, 1992). There are no reports, to our knowledge, of the catalysis of polyphosphate synthesis by iron(II) minerals.…”

Pyrophosphate and Adenosine 5′-Diphosphate Synthesis from Phospho(enol)pyruvate: Catalysis by Phosphate Minerals and Modulation by Dimethyl Sulfoxide

“…Precipitation of calcium was measured using [ 45 Ca]CaCl 2 as tracer, using the same procedure employed for quantifying sedimented [ 32 P]Pi. Determination of absorbed PEP was performed as previously described using a coupled enzyme assay (lactate dehydrogenase plus pyruvate kinase) (Hermes-Lima and Vieyra 1992). Controls for PEP stability in the solutions were assayed as described by Leloir and Cardini (1957).…”

“…If in a such prebiotic system the metabolic products should remain attached and protected to be available for further condensation/polymerization reactions, it is conceivable that an increase of the area on the solid matrix will favor formation and retention of products. In previous work it has been shown that PPi remains bound to the precipitate (Hermes-Lima and Vieyra 1992) and that PPi in solid form can phosphorylate 5Ј-AMP to 5Ј-ADP in a typical condensation reaction (Tessis et al 1995). At higher concentrations of Pi (e.g., 5 mM), PPi formation approaches saturation.…”

“…Examples of catalytic processes involving minerals and energy-donor molecules include the formation of pyrophosphate (PPi) (Krane and Glimcher 1962;Miller and Parris 1964;Hermes-Lima and Vieyra 1992;Vieyra et al 1995) and the synthesis of adenosine 5Ј-diphosphate (5Ј-ADP) on the surface of phosphates (Tessis et al 1995).…”

Phosphate Sorption and Desorption on Pyrite in Primitive Aqueous Scenarios: Relevance of acidic → Alkaline Transitions

“…One way to circumvent this low availability is to propose that insoluble phosphates, both in crystalline and amorphous states, could have participated in phosphoryl transfer reactions. Previous work have shown that: (1) pyrophosphate is formed from crystalline apatite (Miller and Parris, 1964;Vieyra et al, 1995), (2) precipitated calcium orthophosphate can phosphorylate 5 -AMP to 5 -ADP (Tessis et al, 1995), and (3) phosphorolytic cleavage of different phosphorylated compounds occurs with high yield on the surface of minerals (Hermes-Lima and Vieyra, 1992). Phosphorylation should have required concentration excursions of P i in primitive aqueous environment.…”