Fool's gold: ligand-receptor interactions and the origins of life

Abstract

The origins of life is a question that continues to intrigue scientists across disciplines. One theory - the iron-sulphur theory - suggests that reactions essential to the synthesis of biological materials got their catalytic 'spark' from mineral surfaces such as iron pyrite, commonly known as fool's gold. Additionally, the binding affinity of the ligands synthesised in this 'surface metabolism' acted as an early version of natural selection: more strongly-binding ligands were accumulated into further autocatalytic reactions and the aggregation of complex biological materials. Ligand-receptor binding is thus fundamental to the origins of life. In this paper, we use the iron-sulphur theory as a lens through which to review ligand-receptor interactions as they are more commonly understood today. In particular we focus on the electron tunnelling theory of receptor activation that has emerged from research into quantum biology. We revisit criticism against this theory, particularly the lack of evidence for electron transfer in receptors, to see what insights might be offered by ligand-receptor interactions mediated by iron pyrite at the origins of life. What emerges from this comparison is the central importance of redox activity in receptors, in particular with respect to the recurring presence of the disulphide bond. While the paper is a speculative exercise, we conclude that conductivity in biomolecules, particularly the selective conductivity conferred by appropriate ligand-receptor binding, is a powerful tool for understanding diverse phenomena such as pharmacological potency and viral infection. As such it deserves further investigation.