Poly(2‐oxazoline)s (POxs) with 2,2′‐iminodiacetate (IDA) end groups were investigated as inhibitors for laccase. The polymers with the IDA end groups are reversible, competitive inhibitors for this enzyme. The IC50 values were found to be in a range of 1–3 mm. Compared with IDA alone, the activity was increased by a factor of more than 30; thus indicating that attaching a polymer chain to an inhibitor can already improve the activity of the former. The enzyme activity drops to practically zero upon increasing the concentration of the most active telechelic inhibitor, IDA‐PEtOx30‐IDA (PEtOx: poly(2‐ethyl‐2‐oxazoline)), from 5 to 8 mm. This unusual behavior was investigated by means of dynamic light scattering, which showed specific aggregation above 5 mm. Furthermore, the laccase could be stabilized in the presence of POx‐IDA, upon addition at a concentration of 20 mm and higher. Whereas laccase becomes completely inactive at room temperature after one week, the stabilized laccase is fully active for at least a month in aqueous solution.

Controlling the activity of enzymes is an important feature for many processes in medicine, bioanalytics, and biotechnology.S of ar,i th as not been possible to fully switch biocatalystso na nd off by thermoresponsive enzymei nhibitors. Herein, we presentp oly(2-oxazoline)s with iminodiacetic acide nd groups (POx-IDA) that are lower critical solution temperature (LCST) polymers and thus thermosensitive. They are capableo fr eversibly inhibiting the activity of horse radish peroxidase and laccaseb y more than 99 %. Increasingt he temperature makes the POx-IDAp recipitate, which leads to 100 %r ecovery of the enzymea ctivity. This switching cycle is fully reversible.T he LCST of the POx-IDA can be tuned by varying the polymer composition to generate aw ide range of switching windows.