Biochemical evolution III: Polymerization on organophilic silica-rich surfaces, crystal–chemical modeling, formation of first cells, and geological clues

Abstract

Catalysis at organophilic silica-rich surfaces of zeolites and feldspars might generate replicating biopolymers from simple chemicals supplied by meteorites, volcanic gases, and other geological sources. Crystal-chemical modeling yielded packings for amino acids neatly encapsulated in 10-ring channels of the molecular sieve silicalite-ZSM-5-(mutinaite). Calculation of binding and activation energies for catalytic assembly into polymers is progressing for a chemical composition with one catalytic Al-OH site per 25 neutral Si tetrahedral sites. Internal channel intersections and external terminations provide special stereochemical features suitable for complex organic species. Polymer migration along nano͞ micrometer channels of ancient weathered feldspars, plus exploitation of phosphorus and various transition metals in entrapped apatite and other microminerals, might have generated complexes of replicating catalytic biomolecules, leading to primitive cellular organisms. The first cell wall might have been an internal mineral surface, from which the cell developed a protective biological cap emerging into a nutrient-rich ''soup.'' Ultimately, the biological cap might have expanded into a complete cell wall, allowing mobility and colonization of energy-rich challenging environments. Electron microscopy of honeycomb channels inside weathered feldspars of the Shap granite (northwest England) has revealed modern bacteria, perhaps indicative of Archean ones. All known early rocks were metamorphosed too highly during geologic time to permit simple survival of large-pore zeolites, honeycombed feldspar, and encapsulated species. Possible microscopic clues to the proposed mineral adsorbents͞catalysts are discussed for planning of systematic study of black cherts from weakly metamorphosed Archaean sediments.

Impact of mineral micropores on transport and fate of organic contaminants: A review

“…Molecules sorbed in the micropores are also shielded from sunlight and thus protected from photolytic degradation. It has been hypothesized that nanometer to sub-micrometer pores with silica-rich surfaces in various materials from the zeolite, feldspar, and silica mineral groups played a key role in capturing of organic species from aqueous solutions for catalytic assembly into complex biomolecules (such as ribonucleic acids), and protected them from hydrolytic or photochemical destruction, leading to the start of biochemical evolution on Earth (Parsons et al, 1998;Smith, 1998;Smith et al, 1999).…”

The Origin of Life: Chemical Evolution of a Metabolic System in a Mineral Honeycomb?

“…Smith and his coworkers have identified feldspar as the possible honeycomb for the very first stages of biochemical evolution (Parsons et al 1998;Smith 1998;Smith et al 1999). Feldspar is by far the most abundant group of minerals in the earth's crust, forming about 60% of terrestrial rocks crystallize from magma in both intrusive and extrusive igneous rocks; K-feldspars must have been common on the surface of prebiotic Earth *3.8 Ga.…”

Mineral Radioactivity in Sands as a Mechanism for Fixation of Organic Carbon on the Early Earth

“…This mechanism for fixing and concentrating carbonaceous material has the intrinsic advantage that it involves precipitation on a mineral surface, as such surfaces may promote polymer formation (Smith et al, 1999). Although heavy organic compounds have been formed by the irradiation of methane in the laboratory, it has been assumed that the dose rates and carbon concentration required for this to occur are greater than was present on the early Earth, so radioactivity has been considered insignificant as an energy source (Miller and Urey, 1959): The concentrations of radioactive grains provide both a high dose rate and a concentrating mechanism, i.e.…”