Protection of Oxygen-Sensitive Enzymes by Peptide Hydrogel.

Molecular oxygen (O) is a highly reactive oxidizing agent and is harmful to many biological and industrial systems. Although O often interacts metals or reducing agents, a binding mechanism involving an organic supramolecular structure has not been described to date. In this work, the prominent dipeptide hydrogelator fluorenylmethyloxycarbonyl-diphenylalanine is shown to encage O and significantly limit its diffusion and penetration through the hydrogel. Molecular dynamics simulations suggested that the O binding mechanism is governed by pockets formed between the aromatic rings in the supramolecular structure of the gel, which bind O through hydrophobic interactions. This phenomenon is harnessed to maintain the activity of the O-hypersensitive enzyme [FeFe]-hydrogenase, which holds promising potential for utilizing hydrogen gas for sustainable energy applications. Hydrogenase encapsulation within the gel allows hydrogen production following exposure to ambient O. This phenomenon may lead to utilization of this low molecular weight gelator in a wide range of O-sensitive applications.