Artificial Esterase Based on Self-assembly Gel Microspheres Constructed from Chitosan and Amino Acids

A novel artificial esterase based on chitosan and amino acids was synthesized in the present study. The Fmoc-His and Glu were linked to chitosan by active ester method(AEM). The hydroxide radical in chitosan, imidazole group of Fmoc-His and carboxyl from Glu formed a catalytic center of natural esterase. Gel microspheres were coated with a protective layer and a supporting layer by self-assembly construction function in carboxymethylcellulose sodium(CMCS) solution. As for catalytic activity, chitosan-His-Glu was found to be more efficient than chitosan-His and chitosan-Glu in mimicking the core catalytic sites of natural esterase, and the best ratio(mass ratio) of chitosan-His-Glu:CMCS was 1:3. Furthermore, metal ions, such as Ca²⁺, Mg²⁺, Fe²⁺, etc., were able to improve the catalytic efficiency of artificial esterase. And the Lineweaver-Burk plot indicated that the catalytic kinetics of artificial esterase conformed to Michaelis-Menten equation.