A 'superactive' biocatalyst suspended in hydrogel has been made by chemists in China.

Immobilising an enzyme in a hydrogel can dramatically increase the reaction rate, according to Bing Xu and colleagues at The Hong Kong University of Science and Technology.

Enzymes generally perform best in aqueous solvents, as they would be found in nature. Many enzymes don't work well in the organic solvents preferred by chemists, said Xu, and some barely work at all. Xu overcame this problem by immobilising the enzyme inside hydrogel particles, which provide an aqueous environment within the organic solvent. Remarkably, however, one of the immobilised enzymes was actually 'superactive', performing faster than the same enzyme in water.

The reason for the observed superactivity is not yet clear, said Xu. The result could be due to the hydrogel being a favourable environment for the enzyme to work quicker. Alternatively, it could simply be that the substrate accumulates in the hydrogel, increasing the concentration around the enzyme.

The hydrogel is made of self-assembling nanofibres of amino acids. 'The self-assembled nanofibers should offer an opportunity to mimic the ordered arrangement of amino acids found in enzymes,' said Xu, 'providing a platform to develop artificial enzymes.'

James R Mitchell Crow