Chemical conjugation of trypsin with monoamine derivatives of cyclodextrins: Catalytic and stability properties

Bovine pancreatic trypsin was chemically modified by the mono-6-amino-6-deoxy derivatives of α-, β-, and γ-cyclodextrin, using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a coupling agent. The enzyme–cyclodextrin conjugates contained about 2 mol of oligosaccharide per mole of trypsin. The specific esterolytic activity and the affinity of trypsin for substrate were improved by the attachment of the cyclodextrin residues. The thermostability of the enzyme was increased in about 14–17.2 °C after modification. The conjugates prepared were also more stable against thermal incubation at different temperatures ranging from 45 to 60 °C. In comparison with native trypsin, the cyclodextrin–enzyme complexes were about 5.5- to 8.2-fold more resistant to autolytic degradation at pH 9.0.