It is 200 years since Louis Jacques Thenard discovered hydrogen peroxide by reacting barium peroxide with strong acids (L. Thenard Ann. Chim. Phys. 9, 314–317; 1818). Today, about 5 million tonnes of H2O2 is produced every year worldwide. Industry uses it as rocket fuel and a ‘green’ oxidant — for example, for treating wastewater and bleaching pulp and paper.
The molecule occurred in the oceans and in the atmosphere during prebiotic times, 4 billion years ago. At the time, there was no ozone layer and high-intensity ultraviolet irradiation generated the molecule through water radiolysis (J. Haqq-Misra et al. Astrobiology 11, 293–302; 2011). Early life forms soon developed specialized enzymes to break the molecule down into water and oxygen.
In the past 50 years, H2O2 attracted attention in molecular biology, after it was identified as a component of normal cell metabolism. High concentrations contribute to the inflammatory response and low concentrations have a signalling function (see, for example, H. Sies et al. Annu. Rev. Biochem. 86, 715–748; 2017).
This remarkable molecule fulfils the requirements for a biological messenger because it is relatively unreactive (W. H. Koppenol et al. Free Radical Biol. Med. 49, 317–322; 2010). Its enzymatic production and degradation, along with its ability to oxidize highly reactive protein thiol groups, equip it admirably for molecular signalling.
Nature 559, 181 (2018)