Enzymolysis of chitosan by papain and its kinetics

Abstract

Low molecular weight chitosan (LMWC) was obtained by the enzymolysis of chitosan by papain. Enzymolysis conditions (initial chitosan concentration, temperature, pH and ratio of papain to chitosan) were optimized by conducting experiments at three different levels using the response surface methodology (RSM) to obtain high soluble reducing sugars (SRSs) concentrations. Meanwhile, the influence of chitosan substrate concentration on the activity of papain was assessed in the experiments. The enzymolysis process was analyzed using pseudo-first-order and pseudo-second-order kinetic models and the experiment data were found to be more consistent with the pseudo-second-order kinetic model. In addition, the kinetic behavior of the enzymolysis was also investigated by using Haldane model, and chitosan exhibited substrate inhibition. It was clear that the Haldane kinetic model adequately described the dynamic behavior of the chitosan enzymolysis by papain. When the initial chitosan concentration was above 8.0g/L, the papain was overloaded and exhibited significant inhibition.

Keywords: Acetic acid (PubChem CID: 176); Acetyl glucosamine (PubChem CID: 439174); Chitosan; Chitosan (PubChem CID: 21896651); Dinitrosalicylic acid (PubChem CID: 11873); Enzymolysis; Glucose (PubChem CID: 5793); Isodium hydrogen phosphate (PubChem CID: 24203); Kinetics; Monosodium phosphate (PubChem CID: 23672064); Papain; Response surface methodology; Sodium acetate (PubChem CID: 517045); Sodium borohydride (PubChem CID: 22959485); Sodium hydroxide (PubChem CID:14798); d-Glucosamine (PubChem CID: 439213).