Stabilization of α-chymotrypsin by modification with β-cyclodextrin derivatives

Bovine pancreatic alpha-chymotrypsin was chemically modified with two different beta-cyclodextrin derivatives, named mono-6-formyl-beta-cyclodextrin and mono-6-succinyl-6-deoxy-beta-cyclodextrin. The modified enzymes contained approx. 3-5 mol of oligosaccharide/mol of protein, and retained full proteolytic and esterolytic activity. The optimum temperature for or-chymotrypsin was increased by 8 degreesC and its thermostability was enhanced by about 4-6 degreesC after modification. The conjugated enzymes were also more resistant to thermal inactivation at temperatures ranging from 45 to 55 degreesC. Additionally, the modified enzymes were 7-fold more stable against incubation at pH 9.0. The possible influence of supramolecular interactions on the thermal stabilization of modified alpha-chymotrypsins was also studied.