Work

Metal-ion mediated photolytic regulation of diphenylalanine stability: Implications for prebiotic chemical evolution

Year: 2025

Type: article

Abstract: The primordial Earth harbored geologically abundant transition metal ions (e.g., Fe(Ⅲ), Cu(Ⅱ)), which played crucial roles in governing prebiotic photochemical processes, including the stability of key biomolecular building blocks. We systematically investigated the effects of various metal ions on the stability of diphenylalanine under UV radiation (254 nm). Among nine geologically relevant cations examined, Cu(Ⅱ) and Fe(Ⅲ) exhibited significantly different photolytic effects: Fe(Ⅲ) accelerated FF degradation, while Cu(Ⅱ) stabilized FF. Other metal ions had a minimal impact on FF stability. Mechanistic studies have shown that Cu(Ⅱ) and Fe(Ⅲ) exhibit specific coordination with FF. Cu(Ⅱ) preferentially interacts with the amide nitrogen of FF, whereas Fe(Ⅲ) forms complexes centered around oxygen. Furthermore, EPR spectroscopy demonstrated that Fe(Ⅲ) generates higher levels of hydroxyl radicals (⋅OH) in the solution compared to Cu(Ⅱ). This finding establishes the production of reactive oxygen species (ROS) as a key factor driving degradation. This work reveals that the coordination geometry of metals influences photolytic susceptibility through bond-specific activation. Redox-active metals, such as Fe(Ⅲ), enhance degradation through reactive ROS-mediated pathways. Additionally, photostabilization by Cu(Ⅱ) suggests that environments rich in Cu(Ⅱ) mines may help preserve prebiotic FF peptides. By uncovering cation-specific mechanisms of photodegradation at an atomic level, we provide a physicochemical framework that explains how UV filtering via metal complexation may have played a role in the selection and accumulation of proto-biomolecules during the early stages of chemical evolution.

Source: iScience

DOI: 10.1016/j.isci.2025.114432