Polymerized sucrose, previously modified with mono-6-hexylenediamino-6-deoxy-beta-cyclodextrin, was evaluated as thermoprotectant additive for trypsin. Maximal thermal stabilization was achieved by using highly substituted polysaccharides. The catalytic properties of the enzyme were not affected by the presence of the polymer. The optimum temperature for trypsin activity was increased by 10degreesC when adding the beta-cyclodextrin containing polysaccharide. The enzyme thermostability was increased from 48.5 to 64.7degreesC in the presence of the additive. Trypsin was also 22-fold more stable against thermal incubation at 50degreesC when adding the polysaccharide. The protease was sixfold more resistant to autolytic inactivation at alkaline pH in the presence of the beta-cyclodextrin-polysucrose polymer. (C) 2003 Elsevier Inc. All rights reserved.