Abstract: According to the characteristics of molecular structure of chitosan and degradation of chitosan by papain, the “simplified-reverted” simulation was proposed model to simulate the molecular weight distribution (MWD) of chitosan after degradation by papain. First, the sequence distribution of molecular links was simulated and the relationship equation between the degree of deacetylation and the relative content of GlcNAc-GlcN glycosidic linkages of chitosan was set up by Monte Carlo simulation method. Then, the chitosan molecular was advisably simplified, and the MWD of degradation product of simplified chitosan molecular model was obtained by reversion and statistics. In the end, the MWD of degradation product of simplified molecular model was reverted to that of real chitosan molecule. The arithmetic result was obtained integrating the methods of statistics and Monte Carlo to provide a new thinking for simulating the MWD in the degradation products of complex system.

Key words: chitosan, degradation, molecular weight distribution, simulation