Entropy and Charge in Molecular Evolution—the Case of Phosphate

• Published in: Journal of theoretical biology Vol. 187; no. 4; pp. 503 - 522
• Main Authors: Arrhenius, G., Sales, B., Mojzsis, S., Lee, T.
• Format: Journal Article
• Language: English
• Published: Legacy CDMS Elsevier Ltd 21-08-1997
• Subjects: Animals; Biochemical Phenomena; Biochemistry; Entropy; Evolution, Molecular; Exobiology; Ions; Models, Biological; Oceanography; Origin of Life; Phosphates - metabolism; Space life sciences; Non-Nasa Center; Nasa Discipline Exobiology; NASA Discipline Exobiology; Non-NASA Center
• ISSN: 0022-5193; 1095-8541
• DOI: 10.1006/jtbi.1996.0385

Biopoesis, the creation of life, implies molecular evolution from simple components, randomly distributed and in a dilute state, to form highly organized, concentrated systems capable of metabolism, replication and mutation. This chain of events must involve environmental processes that can locally lower entropy in several steps; by specific selection from an indiscriminate mixture, by concentration from dilute solution, and in the case of the mineral-induced processes, by particular effectiveness in ordering and selective reaction, directed toward formation of functional biomolecules.
Numerous circumstances provide support for the notion that negatively charged molecules were functionally required and geochemically available for biopoesis. Sulfate ion may have been important in bisulfite complex formation with simple aldehydes, facilitating the initial concentration by sorption of aldehydes in positively charged surface active minerals. Borate ion may have played a similar, albeit less investigated role in forming charged sugar complexes.
Among anionic species, oligophosphate ions and charged phosphate esters are likely to have been of even more wide ranging importance, reflected in the continued need for phosphate in a proposed RNA world, and extending its central role to evolved biochemistry. Phosphorylation is shown to result in selective concentration by surface sorption of compounds otherwise too dilute to support condensation reaction. It provides protection against rapid hydrolysis of sugars and, by selective concentration, induces the oligomerization of aldehydes. As a manifestation of the life arisen, phosphate already appears in an organic context in the oldest preserved sedimentary record.