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

Bovine pancreatic α ‐chymotrypsin was chemically modified with two different β ‐cyclodextrin derivatives, named mono‐6‐formyl‐ β ‐cyclodextrin and mono‐6‐succinyl‐6‐deoxy‐ β ‐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 α ‐chymotrypsin was increased by 8 °C and its thermostability was enhanced by about 4–6 °C after modification. The conjugated enzymes were also more resistant to thermal inactivation at temperatures ranging from 45 to 55 °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 α ‐chymotrypsins was also studied.