Stabilization of alpha-chymotrypsin by modification with beta-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 alpha -chymotrypsin was increased by 8 degrees C and its thermostability was enhanced by about 4-6 degrees C after modification. The conjugated enzymes were also more resistant to thermal inactivation at temperatures ranging from 45 to 55 degrees C. 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.