A Protein Became a Catalyst When It Formed a Droplet
The researchers built synthetic, resilin-like proteins that gathered into liquid droplets. The same proteins showed little catalytic activity while dispersed in solution. Once they condensed, they began breaking chemical bonds.
Salt supplied a clean control. At concentrations that prevented the proteins from condensing, the catalytic signal disappeared with the droplets.
The Chemistry Happened at the Surface
Measurements placed the catalytic activity at the boundary between each droplet and the surrounding liquid. Reducing the droplets’ total surface area slowed the reaction by 2.44-fold.
The team modeled an electric field of about 10 million volts per centimeter at that boundary. Raman spectroscopy showed that water molecules there formed fewer hydrogen bonds, leaving more water available to take part in bond-cleaving reactions.
A Single Amino Acid Changed the Output
Changing one amino acid at the protein’s exposed end altered the catalytic signal by 8.8-fold. The droplet’s chemistry depended on the molecules presented at its surface, which made the effect tunable rather than incidental.
The Droplets Also Worked Inside Bacteria
The researchers then produced the synthetic droplets inside E. coli. The droplets broke ATP down to adenine and supplied a chemical signal that activated engineered gene circuits in neighboring cells.
Natural Condensates Are the Next Test
These experiments used synthetic proteins and bacterial cells. They establish that phase separation can create a catalytic surface. They leave open whether natural condensates in human cells generate the same chemistry, and whether disease-associated protein assemblies use it.